JPH1176190A - RF coil - Google Patents

Abstract

(57) [Problem] To provide an RF coil having a simple mechanism such that an upper coil is not accidentally dropped on a subject. SOLUTION: When separating an upper coil 2 and a lower coil 1, when the upper coil 2 is pulled straight upward, a groove 81 provided on a fulcrum shaft 8 of a leg portion 7 becomes a guide groove 5 of the lower coil 1. The upper coil 2 is slid along the convex regulating member 6 provided on the upper side to move up. When the fulcrum shaft 8 of the leg 7 comes into contact with the upper part of the guide groove 5 of the lower coil 2, the upper coil 2 can be rotated and opened to the left, and the upper coil 2 and the lower coil 1 are engaged. It is in the state that was done. When the subject's head is placed on the cushion of the lower coil, the upper coil 2
Is rotated to the right, brought to the top of the head, and pressed downward from above, whereby the restricting member 6 and the groove 81 and the guide pin 10 enter along the guide hole 11, and the connector 3,
4 then joins smoothly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a medical diagnostic MRI.
The present invention relates to an RF coil used for a device or the like.

[0002]

2. Description of the Related Art An MRI apparatus for medical diagnosis places an object in a uniform static magnetic field of 0.04 to 2 Tesla, and obtains an image of the distribution of hydrogen nuclei in the object by nuclear magnetic resonance. Morphological information and biochemical functional information can be obtained. The direction of the lines of magnetic force in the static magnetic field is the same as that of the static magnetic field, and the intensity differs depending on the spatial position.By superimposing the weak gradient magnetic field, the magnetic field intensity at each part of the subject is slightly different, so in proportion to it Each part also has a different resonance frequency.

[0003] The frequency difference is discriminated as a position difference, and only the nuclear magnet in a specific slice is selectively excited in response to the resonance frequency being different in the axial direction. A pulse that evenly includes components is applied to a high-frequency magnetic field coil (hereinafter, referred to as an RF coil) wound around the subject.

When a rotating magnetic field having an angular frequency is applied in this way, the nuclear magnet resonates and becomes in a high energy state, and thereafter, T1 (spin-lattice relaxation time), T2
It returns to the original equilibrium state with a time constant called (spin-spin relaxation time). And R wrapped around the subject
An electromotive force is generated in the F coil with the rotation of the nuclear magnet, so that resonance can be electrically observed. The signal attenuated by this time constant is called an FID signal. When this FID signal is subjected to Fourier transform, the density distribution in the cross section of the subject becomes clear. By repeating this operation while changing the gradient direction of the gradient magnetic field, projection images in each direction are obtained. By performing image reconstruction exactly the same as that performed by X-ray CT, the subject can be reconstructed. Is obtained.

As described above, the RF coil has a function of applying a highly stable high-frequency pulse for causing magnetic resonance to a subject and collecting an MR signal from the subject, and the shape thereof is relatively freely selectable. it can. For this reason, if the coil is set so as to be in close contact with the body surface of the imaging site, the MR signal from the target site can be received with high sensitivity, and an image with high resolution can be obtained. As the surface coil, a whole body coil (included in the magnet mount), a body flexible coil, a head coil, a head and neck coil, a target coil, and the like are used.

FIG. 8 shows a conventional RF coil for the head. This RF coil is composed of a lower coil 1 and an upper coil 2 and has a shape such that a head is inserted into a central portion.
3, the lower coil 1 and the upper coil 2 are separated by a hinge 101. When used, the RF coil is first set on a bed, and the upper coil 2 of the RF coil is opened with the hinge 101 as a fulcrum. Next, the subject is laid on the bed and the head is positioned on the lower coil 1 of the RF coil. And
The upper coil 2 covers the head. At this time, the connector 102 of the upper coil 2 is replaced with the connector 103 of the lower coil 1.
Connected to. As described above, the conventional two-piece type head coil is used by connector connection or by completely separating the upper and lower coils without any engagement state.

[0007]

The conventional RF coil is constructed as described above. However, when the upper and lower coils are completely separated without any engagement, the subject is placed on the bed, When the head is placed on the lower coil 1 and the upper coil 2 covers the head, there is a risk that the upper coil 2 will drop onto the subject. Further, in the hinge mechanism as shown in FIG. 8, since the connectors are engaged in an arc-shaped trajectory when they are connected, a connector having a special shape must be provided. If the connector is specially manufactured, there is a problem that the cost increases and the reliability may be reduced.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an RF coil that does not accidentally drop a coil and does not require a special connector.

[0009]

In order to achieve the above object, an RF coil according to the present invention comprises a vertically divided coil, a connecting portion connecting the divided coils at ends, and a linear motion. And the connector has a mechanism that allows a rotational movement for opening and closing and a linear movement for attaching and detaching the connector. Therefore, only the rotational movement can be performed until immediately before the connector of the upper coil is connected to the connector of the lower coil, and only the linear motion can be performed from immediately before the connector is connected to the end thereof, so that the connectors can be smoothly connected to each other.

[0010]

FIG. 1 shows an embodiment of the RF coil according to the present invention. FIG. 2 is a side view, and FIG. 3 shows a state where the upper coil 2 is pulled up. FIG. 4 shows a state in which the upper coil 2 is rotated left and opened. In FIG. 1, the RF coil is composed of an upper coil 2 and a lower coil 1, and has a space in which the head enters the center. The upper coil 2 and the lower coil 1 are electrically connected by connectors 4 and 3. The upper coil 2 includes a leg 7, and the leg 7 is provided with a convex fulcrum shaft 8 and a concave groove 81 on the fulcrum shaft 8 as shown in FIG. 5. On the other hand, the lower coil 1 has
At a position corresponding to the fulcrum shaft 8 of the upper coil 2, a concave guide groove 5 and a convex regulating member 6 as shown in FIG. 6 are provided. The fulcrum shaft 8 of the upper coil 2 fits into the guide groove 5 of the lower coil 1, and the upper coil 2 rotates. Then, the groove 81 on the fulcrum shaft 8 of the upper coil 2 fits into the regulating member 6 on the guide groove 5 of the lower coil 1, and the upper coil 2 can move up and down. Further, a guide pin 10 and a guide hole 11 for vertically guiding the upper coil 2 and the lower coil 1 are provided. Then, a stopper 9 is provided as a contact when the upper coil 2 is opened or closed to the left after being pulled upward, so that the upper coil 2 can be pushed downward at a reliable position.

Next, a procedure for using the RF coil will be described. 1 and 2 show a state in which the upper coil 2 and the lower coil 1 are coupled. First, this RF coil is fixed to the bed of the device. Although the fixing method differs depending on the device, there are a method using a clamp, a screw, a band, and fitting. Next, the upper coil 2 is pulled up. At this time, the groove 81 of the upper coil 2 is
And the guide pin 10 comes out of the guide hole 11. At the same time, the upper connector 4 smoothly separates from the lower connector 3. FIG. 3 shows this state. Next, the upper coil 2 is opened to the left and turned down. At this time, the fulcrum shaft 8 of the upper coil 2 rotates around the upper part of the guide groove 5 of the lower coil 1 as a fulcrum. FIG. 4 shows this state.

Next, the subject is placed on the bed and supine, and the head is placed on the cushion 12 of the lower coil 1. Then, the upper coil 2 is tilted to the right and rotated in the direction of the arrow a until it hits the stopper 9 of the lower coil 1. Then, when the upper coil 2 is lightly pressed downward in the direction of arrow b from above, the groove 81 slides along the regulating member 6, and at the same time the guide pin 10 fits into the guide hole 11 to complete the setting.

Next, the bed table is moved, the head is inserted into the gantry, and the bed is stopped at a predetermined position. The program of the gradient magnetic field that determines the slice plane is set in the state where the slice magnetic field is set in the static magnetic field. Next, a high-frequency pulse including evenly an angular frequency component that selectively excites only the nuclear magnet in the slice is applied to the present RF coil wound around the subject. According to the pulse, an MR signal is induced from the subject to the RF coil. An arbitrary cross-sectional image is obtained by a combination of gradient magnetic fields in three directions (X, Y, Z), and this operation is repeated to obtain a projected image in each direction. This photographing time may be as long as 2 to 20 minutes. The weak induced signal is detected and amplified by a high-sensitivity receiving unit, and an image forming process is performed by a computer.

Since the subject is forced to stand still during the above-mentioned imaging diagnosis, the RF coil is also structured so that the head can rest, and the cushion 12 is inserted in the lower coil. On the other hand, in order to be able to receive MR signals from the subject with high sensitivity, the structure is divided into upper and lower parts so as to be in close contact with the body surface of the imaging part, and a structure that is easy to operate is obtained to obtain a high-resolution image. . When imaging is completed by the above procedure, the bed is separated from the gantry, the table is lowered, the upper coil 2 of the RF coil is pulled upward, opened to the left, the head of the subject is free, and the subject is lowered from the table. .

In the above-described embodiment, the separation mechanism of the two coils when the connector connection is vertical is described. However, the connector connection may be horizontal. FIG. 7 shows an embodiment of an RF coil having this mechanism. In this case, the upper coil 2
When the opening is opened, the groove 81 of the upper coil 2 slides in the horizontal direction (the direction of arrow c) along the regulating member 6 of the lower coil 1 and simultaneously slides on the sliding guide 13.
At this time, the connector connection is smoothly separated. Next, it is confirmed that the upper coil 2 has slid to the left end, and is opened upward and rotated. In this case, the overall length of the RF coil is slightly longer but functionally the same.

Further, the same function can be provided by an RF coil in which a guide groove is provided in the lower coil 1 and a pin is formed in the upper coil 2 to engage with the guide groove. Further, in the above-described embodiment, the head RF coil has been described. However, the present invention can be applied to a coil for a joint or other purposes.

[0017]

The RF coil of the present invention is configured as described above, and the upper coil 2 and the lower coil 1 are in the engaged state. Therefore, there is a danger that the upper coil 2 is erroneously dropped on the subject. There is no. In addition, since the operation can be easily performed only by the rotation and the linear movement of the upper coil 2, and a commercially available standard connector can be used, the cost can be reduced and the reliability can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of an RF coil of the present invention.

FIG. 2 is a diagram showing a side view of the RF coil of FIG. 1;

FIG. 3 is a diagram showing a state where an upper coil of the RF coil of FIG. 1 is raised upward;

FIG. 4 is a diagram showing a state where an upper coil of the RF coil of FIG. 1 is rotated upward;

FIG. 5 is a view showing a leg of an upper coil of the RF coil of FIG. 1;

FIG. 6 is a view showing a guide groove of a lower coil of the RF coil of FIG. 1;

FIG. 7 is a diagram showing another embodiment of the RF coil of the present invention.

FIG. 8 is a diagram showing a conventional RF coil.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Lower coil 2 ... Upper coil 3 ... Lower connector 4 ... Upper connector 5 ... Guide groove 6 ... Restriction member 7 ... Leg 8 ... Support shaft 9 ... Stopper 10 ... Guide pin 11 ... Guide hole 12 ... Cushion 13 ... Sliding guide 81: Groove 101: Hinge 102: Upper connector 103: Lower connector

Claims (1)

[Claims] A coil which is divided into upper and lower parts, a coupling part which couples the divided coils at their ends, and a connector which is detachable by linear motion, wherein the coupling part is a rotary motion for opening and closing. And a mechanism that allows a linear movement for attaching and detaching the connector.