JPH0446726Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

This idea is based on MRI (nuclear magnetic resonance imaging)
The present invention relates to a device, and in particular to its RF antenna.

[Conventional technology]

The RF antenna of an MRI device is used to transmit excitation high-frequency power to a subject such as a human body, or to receive NMR signals from a subject, and two types are being considered: solenoid type and saddle type. . Generally used is a saddle-shaped coil 6 as shown in FIG. This is due to the following circumstances. The direction of the magnetic flux of the RF antenna must be perpendicular to the direction of the static magnetic field. On the other hand, since the static magnetic field must be very strong and uniform, a magnetic field formed inside a solenoid type static magnetic field coil 5 as shown in FIG. 5 is usually used.
Therefore, the subject 4 must be inserted into the static magnetic field coil 5, so the subject 4 lying on the bed with the static magnetic field coil 5 placed horizontally is placed inside. Therefore, in practice,
The direction in which the subject 4 is inserted is limited to the direction Z of the static magnetic field. Therefore, the magnetic flux direction of the RF antenna coil (Y direction in the figure) and the insertion direction Z of the subject are required to be at right angles.
In the case of the saddle-shaped coil 6, the direction of the magnetic flux is perpendicular to the insertion direction Z of the subject 4 (Y direction), so it is necessary to use such a saddle-shaped coil 6. be.

[Problem that the invention attempts to solve]

However, although the saddle-shaped coil certainly satisfies the structural requirement that the subject must be inserted in a direction perpendicular to the direction of the magnetic flux, it has problems in terms of sensitivity and uniformity of transmission or reception. There is a problem that it is not sufficient and is inferior to solenoid type coils. This invention provides an RF antenna for an MRI apparatus that uses a solenoid-type coil that is excellent in sensitivity and uniformity, and that also has a structure that allows insertion of the subject in a direction perpendicular to the magnetic flux direction of the coil. The purpose is to

[Means to solve the problem]

The RF antenna for the MRI apparatus according to this invention consists of a cylindrical coil bobbin, a hole provided on the side of the coil bobbin, and a solenoid-type coil wound around the side of the coil bobbin so as to avoid the hole. .

[Effect]

Since a hole is provided on the side surface of the cylindrical coil bobbin, the subject can be inserted through this hole. A solenoid coil is formed on the side surface of the bobbin so as to avoid the hole. In this case, the direction of the magnetic flux of this solenoid coil is in the axial direction of the cylindrical bobbin, while the insertion direction of the test object is in the direction in which the hole is provided and in the direction perpendicular to the above-mentioned axial direction. be. Therefore, this RF antenna generates magnetic flux in a direction perpendicular to the direction of insertion of the subject, and satisfies the structural requirements regarding the direction of subject insertion and the direction of magnetic flux. Furthermore, since this RF antenna is a solenoid type coil, it has high sensitivity and high uniformity.

【Example】

As shown in FIG. 1, a cylindrical coil bobbin 1 has a hole 2 formed in its side surface and is divided into two parts 11 and 12, which are connected by a hinge 13. And this cylindrical coil bobbin 1
An antenna element 3 is wound around the side surface of the antenna element 3 so as to avoid the hole 2. In this way, a solenoid type coil is formed, and its power feeding point is provided at an appropriate position (not shown). In actual use, as shown in FIG. 2A, one part 11 connected by a hinge 13 is opened from the other part 12, and the subject (for example, the subject's head) is placed inside. and then close both parts 11 and 12 as shown in FIG. 2B. At this time, the subject's neck should be exposed through the hole 2. Then, as shown in FIG. 3, the subject 4 is inserted into the static magnetic field coil 5 in the same direction as the direction Z of the static magnetic field coil 5. Therefore, although the RF antenna according to this embodiment is basically a solenoid type coil,
The direction of the magnetic flux is perpendicular to the insertion direction (Z direction) (Y direction). Therefore, it has high sensitivity and excellent uniformity, and satisfies the conditions regarding the direction of magnetic flux. Furthermore, when the subject is a human head, the entire head is covered with a coil bobbin, which blocks out the loud noises that occur during imaging and attenuates the sound that reaches the subject's ears, causing discomfort. It also has a soothing effect. In the above embodiment, the coil bobbin was divided into two and connected with a hinge, but as shown in FIG. Can be used as In this case, the uniformity is somewhat inferior, but the structure is simpler and it is easier to attach to the subject 4.

[Effect of the idea]

According to the RF antenna of this invented MRI device,
Since it is basically formed by a solenoid type coil, both sensitivity and uniformity are high. Furthermore, the structure allows the subject to be inserted from a direction perpendicular to the direction of the magnetic flux, so there is no problem when actually inserting the subject into the static magnetic field coil. Furthermore, when the subject is a human being and the head is being measured, this head is covered by a coil bobbin, which reduces the amount of noise specific to MRI equipment reaching the ears.
The pain of the subject can be reduced.

[Brief explanation of the drawing]

Figure 1 is a schematic perspective view showing an RF antenna according to an embodiment of this invention, Figures 2A and B are side views for explaining how to use it, and Figure 3 shows the positional relationship with respect to the static magnetic field coil. A schematic perspective view for explanation, FIG. 4 is a schematic perspective view of a modified example, and FIG.
The figure is a schematic perspective view of a conventional example. 1... Cylindrical coil bobbin, 2... Hole, 3...
Antenna element, 4...Object, 5...Static magnetic field coil, 6...Saddle-shaped coil.

Claims (1)

[Scope of utility model registration request] An RF antenna for an MRI apparatus that includes a cylindrical coil bobbin, a hole provided in the side surface of the coil bobbin, and a solenoid-type coil wound around the side surface of the coil bobbin so as to avoid the hole.