JPH07213504A - Rf coil for mr device - Google Patents

Abstract

PURPOSE:To provide an RF coil for an MR device, which can form a capacitor without requiring a chip capacitor of an electronic component, has small variations in respective electrical characteristics, and has stable characteristics. CONSTITUTION:An RF coil 10 for an MR device is characterized in that a capacitor is formed by putting a polyimide film 3 between continuous square copper foil loops 1, 2, and the capacitor and the copper foil loops 1, 2 compose a parallel resonance circuit.

Description

Detailed Description of the Invention

[0001]

This invention relates to an MR (Magnetic Re
More specifically, the present invention relates to an RF (Radio Frequency) coil for a sonance device, and more specifically, for an MR device that can form a capacitor without the need for a chip capacitor of an electronic component, has small variations in individual electrical characteristics, and has stable characteristics. Regarding the RF coil.

[0002]

2. Description of the Related Art An RF coil for an MR device transmits a high frequency magnetic field for excitation to an object in the MR device,
Alternatively, it is a high frequency coil for receiving an NMR signal from the subject.

FIG. 6 shows a conventional RF coil for an MR device disclosed in Japanese Patent Laid-Open No. 5-293093. This RF coil 50 for MR device has metal half loops 51 and 52 formed on both sides of a Teflon base material 53, and a part of these half loops 51 and 52 are opposed to each other with the Teflon base material 53 interposed therebetween to form a capacitor. 54, and an RF coil for an MR device is realized by a series circuit of a half loop 51, a capacitor 54 and a half loop 52.

[0004]

In the above-described conventional RF coil for MR device 50, a part of the half loops 51 and 52 are opposed to each other with the Teflon base material 53 sandwiched therebetween to form the capacitor 54. It has the advantage of not requiring a capacitor. However, there is a problem that variations in individual electrical characteristics of the RF coil for MR device are large. There is also a problem that the stability of characteristics such as temperature coefficient is poor. Therefore, an object of the present invention is to provide an RF coil for an MR device, which can form a capacitor without requiring a chip capacitor for an electronic component, has small variations in individual electric characteristics, and has good stability of characteristics. is there.

[0005]

According to a first aspect of the present invention, there is provided a conductor portion functioning as a coil, and a dielectric portion integrated with the conductor portion to form a capacitor. There is provided an RF coil for an MR device, wherein the inductance and the capacitor are electrically connected in parallel. In a second aspect, the present invention provides an RF coil for an MR device, characterized in that a conductor loop is formed by looping a conductor one or more times to form a conductor loop, and a dielectric layer is sandwiched between the conductors. provide. According to a third aspect, the present invention provides an RF coil for an MR device, characterized in that the conductor loop and the dielectric layer have flexibility in the RF coil for an MR device having the above configuration.

[0006]

In the RF coil for an MR device according to the first aspect, a dielectric portion that is integrated with a conductor portion that functions as a coil to form a capacitor is provided, and the inductance of the conductor portion and the capacitor are electrically connected. In parallel with the MR
Realize a device RF coil. Further, in the RF coil for an MR device according to the second aspect, the conductor is looped at least once to form a conductor loop. Then, a dielectric layer is sandwiched between the conductors to form a capacitor. As a result, a parallel circuit of the inductance of the conductor loop and the capacitor is formed, and the RF for the MR device is formed.
The coil is realized. Therefore, there is an advantage that a chip capacitor for electronic parts is not required. Further, when actually manufactured, variations in individual electric characteristics were small, and those having desired electric characteristics could be preferably manufactured. Further, the stability of characteristics such as temperature coefficient was also good.

In the RF coil for MR device according to the third aspect, the conductor loop and the dielectric layer are made to have flexibility in addition to the above-mentioned function. This can enhance the adhesion to the curved surface of the subject.

[0008]

The present invention will be described in more detail with reference to the embodiments shown in the drawings. The present invention is not limited to this.

First Embodiment FIG. 1A shows an R for MR device according to the first embodiment of the present invention.
3 is a top view of the F coil 10. FIG. In addition, FIG.
It is the perspective view which opened and looked at the RF coil 10 for MR apparatuses.
The RF coil 10 for the MR device is formed by continuously forming rectangular loops 1 and 2 with a thin copper foil.
A polyimide film (for example, Kapton film manufactured by Toray DuPont) 3 is sandwiched between 2 to form a capacitor 4. The copper foil loops 1 and 2 have a thickness of 0.1 mm and a width of 5 m.
m, the length of one side is 40 mm × 40 mm. The sides of the copper foil loops 1 and 2 face each other with the polyimide film 3 interposed therebetween. The polyimide film 3 has a thickness of 0.1 mm, a width of 7 mm, and a side length of 42 mm × 42 mm. With the sizes of the copper foil loops 1 and 2 and the polyimide film 3, the inductance of the copper foil loops 1 and 2 is several 10 m.
H, the capacitance of the formed capacitor becomes several tens of pF to several hundreds of pF, which meets the resonance condition of the MR device.

FIG. 1C is an equivalent circuit diagram of the RF coil 10 for the MR device. An RF coil for the MR device is realized by a parallel circuit of the copper foil loops 1 and 2 and the capacitor 4. As shown in FIG. 2, the signal is transmitted through a matching unit such as a balun.

According to the RF coil 10 for the MR device,
Since the copper foil loops 1 and 2 are opposed to each other with the polyimide film 3 interposed therebetween to form the capacitor 4, the chip capacitor of the electronic component is not required. Further, variations in individual electrical characteristics when actually manufactured are small, and stability of characteristics such as temperature coefficient is good. In addition, the electrical characteristics can be easily adjusted by adjusting the shapes of the copper foil loops 1 and 2 and the thickness and material of the polyimide film 3.

Further, since it has high flexibility, it can be wound around the body B of the subject (patient) to enhance the adhesion, as shown in FIG. Further, as shown in FIG. 4, it can be curved and stored in the endoscope 12. In this case, the flexibility of the endoscope 12 itself is not impaired, and the length of one side of the copper foil loops 1 and 2 can be made larger than the inner diameter of the endoscope 12. In addition, since the space occupied by the endoscope 12 can be reduced, the optical fiber L for illumination necessary for the original function of the endoscope 12 is provided.
F, the observation optical fiber SF, the washing water tube WT, the suction tube ST, the forceps wire PK, etc. can be easily accommodated in the endoscope 12. A Teflon material may be used instead of the polyimide film.

-Second Embodiment- FIG. 5 is a top view showing an RF coil 20 for an MR device according to a second embodiment of the present invention. This RF coil for MR device 2
0 is a structure in which the conductor loop patterns 11 and 12 are formed on both surfaces of the flexible printed circuit board 13 and the conductor loop patterns 11 and 12 are connected by a through hole 21 to form a continuous loop. Conductor loop pattern 1
1 and 12 continuous loops and conductor loop patterns 11 and 12 facing each other with the flexible printed circuit board 13 in between.
With the capacitor 14 according to (1), the same parallel circuit type RF coil for MR device as that of the first embodiment is realized. According to the RF coil 20 for the MR device, since the manufacturing process of the flexible printed board can be utilized,
RF coils for MR devices of the same quality can be mass-produced at low cost.

-Third Embodiment- A spiral conductor loop having a space at the center like a groove of a donut record is formed, and a dielectric film is sandwiched between the loops to form a capacitor. The parallel circuit of the capacitor and the loop makes it possible to use the RF for MR device.
You may implement a coil. In this case, the loop can be easily manufactured by punching the conductor film.

[0015]

According to the RF coil for MR device of the present invention, a capacitor can be formed without the need for a chip capacitor for electronic parts. Further, it is possible to reduce variations in individual electric characteristics and improve stability of characteristics.

[Brief description of drawings]

FIG. 1 is a top view, a perspective view and a circuit diagram of an RF coil for an MR device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of signal transmission to the RF coil for the MR device of the first embodiment.

FIG. 3 is an explanatory view of a state where the RF coil for MR device of the first embodiment is curved.

FIG. 4 is an explanatory diagram showing a state in which the RF coil for MR device of the first embodiment is curved and housed in an endoscope.

FIG. 5 is a top view of an RF coil for an MR device according to a second embodiment of the present invention.

FIG. 6 is a perspective view and a circuit diagram showing an example of a conventional RF coil for an MR device.

[Explanation of symbols]

 10,20 RF coil for MR device 1,2,11,12 Loop 3 Dielectric film 4,14 Capacitor 13 Flexible printed circuit board

Claims (3)

[Claims] 1. A conductor part functioning as a coil and a dielectric part which is integrated with the conductor part to form a capacitor are provided, and the inductance of the conductor part and the capacitor are electrically connected in parallel. R for MR device characterized by
F coil. 2. An RF coil for an MR device, comprising: forming a conductor loop by looping a conductor in one or more loops, and sandwiching a dielectric layer between the conductors. 3. The RF coil for an MR device according to claim 2, wherein the conductor loop and the dielectric layer have flexibility.