JP2001070281A - Rf coil for mri and method of regulating resonance frequency thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily perform the regulating work of resonance frequency at a low cost by mounting a socket or connector on a coil conductor, and attachably and detachably mounting a capacitor board having a capacitor thereon on the socket or connector. SOLUTION: An RF coil for MRI 100 comprises to coil conductor 1 having the fixed capacitor 2, and the socket 3 provided on a part of the coil conductor 1. The capacitor board 10 having a fixed capacitor 11 thereon is mounted on the coil conductor 1 attachable to and detachable from the socket 3. The used fixed capacitor 2 shares the fixed portion of the resonance frequency, and the fixed capacitor 11 is provided in order to share the variable portion of the resonance frequency. The socket 3 has a number of pins raised thereon, and the pins are inserted to a number of holes of the capacitor board 10, whereby the coil conductor 1 is electrically connected to the capacitor 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an MRI RF coil and a method of adjusting the resonance frequency thereof, and more particularly, it can reduce the cost of parts, simplify the operation of adjusting the resonance frequency, and shorten the adjustment time. MRI
The present invention relates to an RF coil for use and a resonance frequency adjusting method thereof.

[0002]

2. Description of the Related Art FIG. 5 is an explanatory view showing a conventional MRI RF coil and a method of adjusting its resonance frequency. This M
The RI RF coil 500 includes a coil conductor 1, a fixed capacitor 2, and a trimmer capacitor 53 that is a variable (semi-fixed) capacitor. The fixed capacitor 2
Shares a fixed portion of the resonance frequency, and the trimmer capacitor 53 shares a variable portion of the resonance frequency.

[0003] The resonance frequency of the MRI RF coil 500 is adjusted by connecting a resonance frequency measuring device MX to the MRI RF coil 500 and using the MRI RF coil 500.
The trimmer capacitor 53 is adjusted so that the resonance frequency matches the strength of the magnet of the RI device. The strength of the magnet is heard from a hospital where the MRI apparatus is installed or measured.

[0004]

The above-mentioned conventional MRI R
The F coil 500 requires the trimmer capacitor 53. However, since the nonmagnetic and high withstand voltage trimmer capacitor is expensive, there is a problem that the cost increases. In addition, in the above-described method for adjusting the resonance frequency of the MRI RF coil 500, the operation steps of connecting the resonance frequency measuring device MX, adjusting the trimmer capacitor 53, and then removing the resonance frequency measuring device MX are complicated. However, there is a problem that the adjustment time is long. SUMMARY OF THE INVENTION It is an object of the present invention to provide an MRI RF coil and a resonance frequency adjustment method capable of reducing the cost of parts, simplifying the operation of adjusting the resonance frequency, and shortening the adjustment time.

[0005]

According to a first aspect of the present invention, there is provided a coil conductor, a socket or connector attached to the coil conductor, and a capacitor board mounted with a capacitor and detachable from the socket or connector. An MRI RF coil provided with: In the MRI RF coil according to the first aspect, a socket or a connector is attached to the coil conductor, and a capacitor board is attached to or detached from the socket or the connector. Since this capacitor board can be manufactured at a lower cost than a trimmer capacitor, component costs can be reduced. In the above configuration, the term "socket or connector" is used, but this broadly means connection means for detachably mounting the coil conductor and the capacitor board, and is not limited to the narrow sense of "socket or connector". Absent.

According to a second aspect, the present invention provides a plurality of capacitor boards according to claim 1 on which capacitors having different capacities are respectively mounted, and an MRI R board according to claim 1.
Provided is a method of adjusting the resonance frequency of an RF coil for MRI, comprising selecting a capacitor board equipped with a capacitor having a capacity suitable for the strength of a magnet of an MRI apparatus using an F coil and mounting the capacitor board. . In the method of adjusting the resonance frequency of an MRI RF coil according to the second aspect, a capacitor having a capacity suitable for the strength of a magnet of an MRI apparatus using an MRI RF coil is selected from a capacitor board on which capacitors having different capacities are mounted. A capacitor board with a capacitor was selected and mounted on a socket or connector. According to this, it is only necessary to select and mount the capacitor board, there is no need to connect or disconnect the resonance frequency measuring device, and it is not necessary to adjust the trimmer capacitor while looking at the resonance frequency measuring device, The process can be simplified and the adjustment time can be shortened.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention shown in the drawings will be described below. Note that the present invention is not limited by this. FIG. 1 shows an MRI according to an embodiment of the present invention.
FIG. 3 is a perspective view of an RF coil for use. The MRI RF coil 100 includes a coil conductor 1, a fixed capacitor 2, a socket 3 attached to the coil conductor 1, and a capacitor board 10 on which a fixed capacitor 11 is mounted and which is detachable from the socket 3. ing. The fixed capacitor 2 shares a fixed portion of the resonance frequency, and the fixed capacitor 11 shares a variable portion of the resonance frequency.

FIG. 2 is a perspective view of a main part showing a state before the capacitor board 10 is mounted on the MRI RF coil 100. Pins 5 are erected on the socket 3, and these pins 5 are connected to holes 15 of the capacitor board 10.
When the coil conductor 1 and the capacitor 11 are electrically connected to each other, the capacitor board 10 is mounted.

FIG. 3 is a view showing an example of the resonance frequency corresponding to the capacitance of the capacitor 11 mounted on the capacitor board 10. First, the capacitance of the fixed capacitor 2 is determined so that the resonance frequency becomes 8,550 kHz when the capacitance of the capacitor 11 mounted on the capacitor board 10 is 100 pF. The capacitors 11 mounted on the capacitor boards 10 have different capacities such that the resonance frequency differs at intervals of 10 kHz. For example, when the capacitance of the capacitor 11 is C6, the resonance frequency is 8,560 kHz.

FIG. 4 is a frequency characteristic diagram of S / N (signal noise ratio). MRI from resonance frequency fo of MRI system
When the resonance frequency of the RF coil 100 for use is separated by 20 kHz, the S / N is reduced by about 5%. Therefore, when the capacitance of each of the capacitors 11 mounted on the capacitor board 10 is changed in steps of the resonance frequency of 10 kHz, the deviation of the resonance frequency of the MRI RF coil 100 from the resonance frequency fo of the MRI apparatus is 5 kHz at the maximum. Therefore, FIG.
From the characteristics described above, the reduction in S / N is about 1.5% at the maximum. However, such a decrease in S / N may be ignored.

The resonance frequency of the MRI RF coil 100 is adjusted as follows. (1) Ask the hospital where the MRI apparatus is installed or measure it to check the strength of the magnet. (2) Calculate the resonance frequency fo from the strength of the magnet. (3) RF coil 1 for MRI at calculated resonance frequency fo
A capacitor board 10 on which a capacitor 11 having a capacity such that the resonance frequency of 00 is closest is selected and mounted.

For example, if the resonance frequency fo calculated from the strength of the magnet is 8,558 kHz, the capacitor board 10 having the capacitor 11 of the capacitance C6 shown in FIG.
Is selected and attached. In this case, the deviation of the resonance frequency of the MRI RF coil 100 from the resonance frequency fo of the MRI apparatus is 2 kHz. Therefore, from the characteristics shown in FIG. 4, the reduction in S / N is about 0.5%. This reduction in S / N is negligible.

[0013]

According to the RF coil for MRI and the method of adjusting the resonance frequency of the MRI according to the present invention, a capacitor board having a capacitor having a capacity suitable for the strength of the magnet of the MRI apparatus using the RF coil for MRI is selected. Since the adjustment of the resonance frequency is completed only by the mounting work, the working process can be simplified and the adjustment time can be shortened. Further, since an expensive trimmer capacitor is not required, the cost of parts can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view of an MRI RF coil according to an embodiment of the present invention.

FIG. 2 RF for MRI before mounting a capacitor board
It is a principal part perspective view of a coil.

FIG. 3 is a graph showing a relationship between a capacitance of a capacitor mounted on a capacitor board and a resonance frequency.

FIG. 4 is a graph showing a relationship between a shift between a resonance frequency of the MRI apparatus and a resonance frequency of the MRI RF coil and S / N.

FIG. 5 is an explanatory view of a conventional MRI RF coil and its resonance frequency adjusting method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coil conductor 2 Fixed capacitor 3 Socket 5 pin 10 Capacitor board 11 Fixed capacitor 12 hole

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshifumi Higa 4-7, Asahigaoka, Hino-shi, Tokyo 127 G-F Yokogawa Medical System Co., Ltd. F-term (reference) 4C096 AB42 CC15 CC17 CC40

Claims (2)

[Claims] 1. An MRI RF coil comprising: a coil conductor; a socket or a connector attached to the coil conductor; and a capacitor board on which a capacitor is mounted and which is detachable from the socket or the connector. 2. A plurality of capacitor boards according to claim 1, wherein capacitors having different capacities are mounted, respectively.
An MRI using the MRI RF coil according to claim 1.
A method for adjusting a resonance frequency of an MRI RF coil, comprising selecting a capacitor board having a capacitor having a capacity suitable for the strength of a magnet of the apparatus, and mounting the capacitor board.