JP2003010146A - Rf coil and mri system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an RF coil imparting no sense of oppression to a subject, and easy in position-adjusting an imaging part of the subject and a coil circuit. SOLUTION: The RF coil C has an either of transparent or semitransparent cover having first to sixth side coils 101, 102, 103, 104, 105, and 106 for covering up to tiptoe from the jaws. This coil images the whole body of the subject at once while moving a cradle. The imaging part of the subject and the coil can be easily position-adjusted, and a sense of oppression is not imparted to the subject.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an RF coil and an MRI apparatus provided so as to wind a subject.

[0002]

2. Description of the Related Art Magnetic resonance imaging (MRI: Magneti)
c Resonance Imaging)
An object to be imaged is carried into an internal space of a magnet system, that is, an imaging space in which a static magnetic field is formed, and a gradient magnetic field and a high frequency magnetic field are applied to generate magnetic resonance signals from spins in the object. , Reconstruct an image based on the received signal.

The high frequency magnetic field is applied as an RF pulse (plse). Application of RF pulse is also called transmission of RF signal. The magnetic resonance signal is received as an RF signal.
An RF coil is used for transmitting and receiving RF signals.

There are RF coils for transmission only, those for reception only, and those for both transmission and reception. As for the RF coil dedicated to reception and used for both transmission and reception, those having various shapes are prepared according to the region to be imaged. Such RF
As one of the coils, as shown in FIG. 5A, there is an RF coil 1 having a cylindrical body.

[0005]

However, the conventional tubular RF coil 1 has a structure in which the coil circuit is sandwiched between covers of opaque resin, and the coil circuit cannot be visually recognized from the outside. There is a problem in that it is difficult to align the imaged part of (1) with the coil circuit of the RF coil 1.

Further, in recent years, a technique has been established in which a whole body of a subject is imaged at once while moving a cradle on which the subject is placed. In this case, FIG. 5 (b)
As shown in the figure, a cylindrical RF coil 5 that covers the whole body of the subject 3 and has a plurality of coil circuits 5a inside is required.

R which covers the whole body of the subject 3
When the F coil 5 is used, the cover is opaque,
There is also a problem of giving the subject 3 a feeling of pressure. In addition, it is necessary to perform the alignment a plurality of times, and it is necessary to repeatedly attach and detach the RF coil 5 to perform the alignment.

The present invention has been made in view of the above problems, and a first object thereof is to provide an RF coil which facilitates alignment between an imaging region of a subject and a coil circuit.

A second object is to provide an RF coil which does not give a feeling of pressure to the subject.

[0010]

The above-mentioned problems can be solved by the following inventions. (1) The invention according to a first aspect is an RF coil provided so as to wind a subject, the RF coil comprising a transparent or semitransparent cover for covering the coil circuit. .

By providing either the transparent or the semi-transparent cover for covering the coil circuit, it becomes easy to align the imaging portion of the subject with the coil circuit. In addition, it feels light to the eye and does not give the subject a feeling of pressure. (2) The invention of a second aspect comprises a first coil portion having a half-split cylinder shape, and a second coil portion having a half split cylinder shape and forming a cylinder with the first coil portion. (1)
It is the described RF coil. (3) The invention of a third aspect is characterized in that at least one of the first coil portion and the second coil portion has the transparent or translucent cover ( 2) The RF coil described above.

At least one of the first coil portion and the second coil portion has a cover that is either transparent or translucent, so that the position of the imaging region of the subject and the coil circuit can be improved. Matching becomes easy.

Further, the invention according to the fourth aspect, which does not give a feeling of pressure to the subject, is characterized in that the material of the cover is a semitransparent FRP (1) to (3). The RF coil according to claim 1.

The material of the cover is a semi-transparent FRP (Fi
It is lightweight and durable due to its ber reinforced plastics. (5) The invention according to a fifth aspect provides the RF coil according to any one of (1) to (4), which covers the subject from the chin to the toes. (6) The invention according to a sixth aspect is the RF coil according to any one of (1) to (5), which has a plurality of coil circuits along the body axis direction of the subject.

By having a plurality of coil circuits along the body axis direction of the subject, the whole body of the subject can be imaged at one time while moving the cradle on which the subject is placed. (7) The invention according to a seventh aspect is the RF coil according to (1) or (2), characterized in that the coil circuit is a saddle coil. (8) The invention according to an eighth aspect is characterized by including the RF coil according to any one of (1) to (7).
It is a device.

(1) R according to any one of 1 to 7
By having the F coil, it becomes easy to position the imaging region of the subject and the coil circuit. In addition, it does not give a feeling of pressure to the subject.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to the drawings. First, the block of the MRI apparatus of the embodiment, that is, the magnetic resonance imaging apparatus.
The overall configuration will be described with reference to FIG.

As shown in the figure, the apparatus has a magnet system 100.
The magnet system 100 is a main magnetic field coil.
102, gradient coil 122 and RF (radio f
frequency) coil 124. Each of these coils has a substantially cylindrical shape and is arranged coaxially with each other.

The subject 1 is mounted on a cradle 500 in a generally cylindrical internal space (bore) of the magnet system 100 and is carried in and out by a carrying means (not shown). An RF coil 110 covering the chin to the toes is attached to the subject 1. R
The F coil 110 will be described later again.

The main magnetic field coil 120 forms a static magnetic field in the internal space of the magnet system 100. The direction of the static magnetic field is substantially parallel to the direction of the body axis of the subject 1. That is, a so-called horizontal magnetic field is formed. The main magnetic field coil 120 is configured by using, for example, a superconducting coil. Needless to say, a normal conductive coil or the like may be used instead of the superconductive coil. The main magnetic field coil 120 is an example of an embodiment of the static magnetic field forming means in the present invention.

The gradient coil 122 produces three gradient magnetic fields for imparting gradients to the static magnetic field strength in the directions of three mutually perpendicular axes, ie, the slice axis, the phase axis and the frequency axis.

When the mutually perpendicular coordinate axes in the static magnetic field space are x, y, and z, any axis can be a slice axis. In that case, one of the remaining two axes is the phase axis and the other is the frequency axis. Further, the slice axis, the phase axis, and the frequency axis can be made to have arbitrary inclinations with respect to the x, y, and z axes while maintaining the verticality among them.

The gradient magnetic field in the slice axis direction is also called a slice gradient magnetic field. The gradient magnetic field in the phase axis direction is also referred to as a phase encode gradient magnetic field. Read out the gradient magnetic field in the frequency axis direction.
t) Also called a gradient magnetic field. In order to enable the generation of such a gradient magnetic field, the gradient coil 122 has three system gradient coils (not shown). Hereinafter, the gradient magnetic field is also simply referred to as a gradient.

The RF coil 124 is provided in the static magnetic field space for the subject 1
A high-frequency magnetic field is generated to excite spins in the human body. The RF coil 110 receives an electromagnetic wave generated by the excited spin, that is, a magnetic resonance signal. RF
The coil 110 can also transmit an RF excitation signal.

A gradient drive unit 130 is connected to the gradient coil 122. The gradient driver 130 includes a gradient coil 122.
A drive signal is applied to the to generate a gradient magnetic field. The gradient drive unit 130 has three-system drive circuits (not shown) corresponding to the three-system gradient coils in the gradient coil 122.

An RF drive unit 140 is connected to the RF coils 124 and 110. The RF driving unit 140 applies a driving signal to the RF coil 124 or the RF coil 110 to generate R
The F pulse is transmitted to excite the spin in the body of the subject 1.

The RF coil 110 has a data collecting section 150.
Are connected. The data collection unit 150 samples the reception signal received by the RF coil 110 (sample).
ing) and collect it as digital data.

A control unit 160 is connected to the gradient drive unit 130, the RF drive unit 140, and the data collection unit 150. The controller 160 controls the gradient driver 130 and the data collector 150 to perform imaging.

The control unit 160 is, for example, a computer (c
computer) and the like. Control unit 160
Has a memory (not shown). The memory stores a program for the control unit 160 and various data. The function of the control unit 160 is realized by the computer executing the program stored in the memory.

The output side of the data collecting section 150 is connected to the data processing section 170. The data collected by the data collection unit 150 is input to the data processing unit 170. The data processing unit 170 is configured using, for example, a computer or the like. The data processing unit 170 has a memory (not shown). The memory stores programs for the data processing unit 170 and various data.

The data processing section 170 is connected to the control section 160. The data processing unit 170 is above the control unit 160 and controls it. The function of this apparatus is realized by the data processing unit 170 executing a program stored in the memory.

The data processing section 170 includes a data collection section 15
0 stores the collected data in memory. A data space is formed in the memory. This data space constitutes a two-dimensional Fourier space. Hereinafter, the Fourier space is also referred to as k-space. The data processing unit 170 performs a two-dimensional inverse flow on the k-space data.
An image of the subject 1 is reconstructed by Rie conversion.

A display unit 180 and an operation unit 190 are connected to the data processing unit 170. The display unit 180 includes a graphic display.
ay) and the like. The operation unit 190 includes a keyboard having a pointing device and the like.

The display section 180 displays the reconstructed image and various information output from the data processing section 170. The operation unit 190 is operated by the user and inputs various commands and information to the data processing unit 170. A user interactively operates the apparatus through the display unit 180 and the operation unit 190.

Next, the RF coil 110 will be described with reference to FIG. The RF coil 110 includes a first coil portion 110a having a half-split cylinder shape and a first coil portion 11 having a half-split cylinder shape.
0a and a second coil portion 110b forming a tubular body.

In this embodiment, the total length is about 150 cm,
The cross-sectional shape was an ellipse with a short diameter of about 30 cm and a long diameter of about 40 cm, and was covered from the chin of the subject to the toes. At this time, in order to allow the arm of the subject to be exposed to the outside from the side of the RF coil 110, a cutout portion where the arm of the subject is exposed may be formed on the side of the RF coil 110.

Further, when the second coil portion 110b is set on the first coil portion 110a, a locking tool for fixing the two is provided. Six coil circuits are provided inside the first and second coil units 110a and 110b, respectively, and the first to sixth saddle coils (saddle coils) are provided.
coil) 101, 102, 103, 104, 10
5, 106 are formed.

Then, as shown in FIG. 3, which is a sectional view taken along the line AA in FIG. 2, the first to sixth saddle coils 10 are shown.
1, 102, 103, 104, 105 and 106 are covered with FRP covers 111 and 111 'which are made of a semitransparent material.

When the subject 1 is imaged using the RF coil 110 having such a configuration, the subject 1 is attached to the second coil portion 110b of the RF coil 110 fixed to the cradle 500, as shown in FIG. The first coil part 1
Set 10a.

Then, the cradle 500 is moved in order to align the imaged region of the subject 1 with the landmark emitted from the projector 100a. With such a configuration, the coil circuit is covered with the translucent FRP covers 111 and 111 ', so that the subject is not given a feeling of pressure.

Further, by covering the coil circuit with the semi-transparent FRP covers 111 and 111 ', it is possible to easily know which part of the subject 1 the landmark is irradiated with, and the imaging region of the subject 1 and the coil. The alignment with the circuit becomes easy.

In particular, in the case of the RF coil 110 having a plurality of coil circuits as in the above configuration, as shown in FIG. 2, for example, the third, fourth, fifth and sixth saddle coils 10 are used.
Imaging at imaging center I using 3, 104, 105 and 106, second, third, fourth and fifth saddle coils 120, 1
Imaging at the imaging center II using 03, 104, 105
First, second, third and fourth saddle coils 101, 10
By moving the cradle 500 for imaging at the imaging position III using 2, 103 and 104, it is possible to image the whole body of the subject 1 at one time.

The present invention is not limited to the above embodiment. In the above-described embodiment, the RF coil having a plurality of coil circuits has been described. However, even when the RF coil having one coil circuit described in the conventional example is applied, a subject does not feel a sense of pressure, It becomes easy to align the imaging region of the subject with the coil circuit.

Further, in the above embodiment, both the first coil portion 1101 and the second coil portion 1102 are semitransparent F.
Although the coil circuit was covered with the RP cover, the first coil unit 1
Even if only 101 is used, compared to the conventional opaque cover, the subject is not given a feeling of pressure, and the alignment of the imaging region of the subject and the coil circuit is facilitated.

Further, although the cover material is semi-transparent FRP in the above embodiment, it may be transparent.

[0046]

As described above, according to the present invention, it is possible to realize an RF coil that does not give a feeling of pressure to a subject and facilitates the alignment between the imaging region of the subject and the coil circuit.

[Brief description of drawings]

FIG. 1 is a block diagram of an MRI apparatus according to an embodiment.

FIG. 2 is a diagram illustrating the RF coil of FIG.

3 is a cross-sectional view taken along the section line AA of FIG.

FIG. 4 is a diagram illustrating imaging using the RF coil of FIG.

FIG. 5 is a diagram illustrating a conventional RF coil.

[Explanation of symbols]

101, 102, 103, 104, 105 saddle coil 111, 111 'cover

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akira Nabeya             127, 4-7 Asahigaoka, Hino City, Tokyo             GE Yokogawa Medical System Co., Ltd.             Within (72) Inventor Atsushi Nozaki             127, 4-7 Asahigaoka, Hino City, Tokyo             GE Yokogawa Medical System Co., Ltd.             Within F-term (reference) 4C096 AA01 AB47 AB50 AD10 AD24                       BB40 CA02 CA03 CA15 CC02                       CC12 CC40

Claims (8)

[Claims] 1. An RF provided so as to wind a subject.
An RF coil comprising a transparent or semi-transparent cover for covering a coil circuit. 2. A first coil part having a half-split cylinder shape, and a second coil part having a half-split cylinder shape and forming a cylinder with the first coil part. The RF coil according to item 1. 3. The RF coil according to claim 2, wherein at least one of the first coil portion and the second coil portion has the transparent or semi-transparent cover. . 4. The RF coil according to claim 1, wherein a material of the cover is semitransparent FRP. 5. The RF according to any one of claims 1 to 4, which covers the subject from the chin to the toes.
coil. 6. The RF coil according to claim 1, which has a plurality of coil circuits along a body axis direction of the subject. 7. The R according to claim 1, wherein the coil circuit is a saddle coil.
F coil. 8. The RF according to any one of claims 1 to 7.
An MRI apparatus having a coil.