JPH05317284A - Receving coil mri device - Google Patents

Abstract

PURPOSE:To improve S/N by constituting a receiving QD coil of an MRI device consisting of two coils in which the sensitivity directions are orthogonal to each other, so that it can be installed in an examinee by allowing it to adhere closely. CONSTITUTION:On a non-conductive coil sheet 70 having flexibility, a solenoid coil 100 and a saddle type coil 200 in which the receiving directions are orthogonal to each other are formed, and in the part in which the solenoid coil 100 and the saddle type coil 200 intersect with each other, supporting plates 51a, 51b having rigidity to the extent that they are not deformed even if the coil sheet 70 is wound round cylindrically are provided, and by these supporting plates 51a, 51b, a degree of freedom of deformation of the coil sheet 70 becomes small. In such a way, the coil comes to adhere closely and easily to the examinee due to flexibility of the coil sheet 70, strain deformation of the coil is suppressed by rigidity of the supporting plate, by which orthogonality of the coil becomes satisfactory, and S/N can be improve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving coil of a magnetic resonance imaging apparatus (hereinafter, referred to as an MRI apparatus), and more particularly to a receiving coil having flexibility which can be closely attached to a subject.

[0002]

2. Description of the Related Art An MRI apparatus raises a subject into a strong and uniform static magnetic field space formed by a magnet for generating a static magnetic field, applies a high frequency magnetic field and a gradient magnetic field to the subject according to a predetermined pulse sequence, and A magnetic resonance (hereinafter referred to as NMR) phenomenon is caused in a nuclear spin of a specific cross section, an NMR signal generated as a result is detected, and the detected signal is reconstructed by a two-dimensional Fourier transform method or the like to display a tomographic image. To do. The detection of the NMR signal is performed by disposing a high-frequency receiving coil in the vicinity of the subject, but conventionally, a pair of coils, for example, a solenoid coil or a saddle type coil is used to receive the unidirectional NMR signal. In order to improve the method and the S / N, a method is adopted in which the sensitivity directions of the two sets of coils are made orthogonal to each other and the bidirectional NMR signals are received. In the case of the latter case, the reception direction of the two pairs of coils is orthogonal to the static magnetic field direction, so QD (Quardrature Detectio)
n) It is called a coil.

Conventional QD coils include a saddle type coil and a saddle type coil for the horizontal magnetic field type, and a solenoid coil and a saddle type coil for the vertical magnetic field type. Proposed. M
The sensitivity of the receiving coil in the RI apparatus is improved to such an extent that it is brought into close contact with the subject, and thus the S / N is also improved, but the conventional QD coil described above is manufactured by winding a coil on a bobbin that is made of resin and lacks flexibility. It was something that was done. For this reason, it is difficult to bring the coil into close contact with the subject, and the sensitivity and S / N cannot be said to be so excellent.

[0004]

In order to bring the coil into close contact with the subject and to improve the sensitivity and S / N of the coil, it is necessary to give flexibility to the coil portion. However, if the coil is made flexible, in the case of the QD coil, a coupling (coupling) of two sets of coils occurs, which becomes a problem. Coupling means that when a high-frequency current is applied to one coil, it leaks to the other coil. The cause of the coupling is that the distance between the intersecting parts of each coil is close to several mm. .. For the coupling,
Capacitive coupling due to stray capacitance and inductive coupling that couples to the other side by the magnetic flux generated by one coil are considered. The inductive coupling can be adjusted by placing a good conductor, for example, a copper plate near the coil to balance the magnetic flux. Further, the capacitive coupling cannot be adjusted by this method, but it can be dealt with by making the stray capacitance between the coils as small as possible beforehand. However, such adjustment and correspondence can be made with the precondition that the shape of the coil is constant.

If the coil has only flexibility, it has a large degree of freedom of deformation and is easily deformed. When deformed, the magnetic flux balance is lost and the coupling becomes large. Coupling of the coils means that the other side is a load on each coil, and the S / N of the detection is lowered, and the image is deteriorated. Due to the above problems, a flexible receiving QD coil for an MRI apparatus has not been realized.

An object of the present invention is to solve the above-mentioned problems, to provide a flexible QD coil for reception of an MRI apparatus, and to provide a coil capable of coping with a change in the size of a subject. Especially.

[0007]

In order to achieve the above object, the present invention provides a receiving coil for an MRI apparatus which is mounted on a subject and detects a magnetic resonance signal, wherein the receiving direction is orthogonal to the static magnetic field direction, and Two sets of coil systems whose reception directions are orthogonal to each other are formed by arranging a non-conductive flexible part and a non-conductive rigid part, and are arranged on a coil holding member which can be formed in a tubular shape in the arranging direction. (Claim 1). Further, the present invention achieves the object by forming a coil holding member in a band shape in the above coil and providing connectors at both ends of the coil holding member for connecting and disconnecting each of the two sets of coil systems. (Claim 2). Furthermore,
According to the present invention, in the above coil, two sets of coil systems are a solenoid type coil and a pair of saddle type coils orthogonal to the solenoid type coil, and an intersection of the solenoid type coil and the saddle type coil is formed in the rigid portion. To achieve the purpose (claim 3). Further, the present invention achieves the object by intersecting each coil member at the intersection of the solenoid type coil and the saddle type coil with an interval of at least 5 mm (claim 4).

Further, in order to achieve the above object, the present invention is an MR which is mounted on a subject to detect a magnetic resonance signal.
In the receiver coil for the apparatus I, a coil holding member in which a pair of non-conductive and rectangular rigid members and a pair of non-conductive and rectangular flexible portions are arranged to face each other, and a receiving direction to the coil holding member is a static magnetic field direction. Two sets of coil systems which are orthogonal to each other and whose receiving directions are orthogonal to each other are provided, and the coil system has a structure in which each part of the coil holding member can be connected or disconnected by a connector, and has a coil member and a connector. A plurality of types of flexible members having different lengths are provided.

[0009]

In the invention according to claim 1, in the coil holding member provided with two sets of coil systems in which the receiving direction is orthogonal to the static magnetic field direction and the receiving directions are orthogonal to each other, the flexible portion and the rigid portion are It is arranged so that it can be formed in a cylindrical shape in the arrangement direction. The flexible portion of the coil holding member is used when winding the coil around the subject.
The rigid portion serves to facilitate the close contact of the coil with the subject, and the rigid portion limits the degree of freedom of deformation of the coil. Therefore, by setting the lengths of the flexible portion and the rigid portion to be appropriate lengths according to the region to be imaged, a QD coil with good performance can be obtained.

According to the second aspect of the present invention, the connectors provided at both ends of the coil holding member formed in the shape of a band are mounted on the imaging site such that the coil cannot be fitted onto the subject in a fitting manner. To facilitate.

In the invention according to the third aspect, the intersection of the two sets of the solenoid type coil and the saddle type coil of the coil system is provided in the rigid portion. Coupling of the coils of the set occurs. By providing the intersecting portion in the rigid portion, deformation is less likely to occur. In the invention of claim 4, the coupling is prevented by setting the interval between the coil members of the two coil systems that intersect with each other to 5 mm or more.

In the invention according to the sixth aspect, two pairs of the rigid member and the flexible member are separated from each other, two sets of coil systems are arranged in each of these members, and they are connected by a connector or In addition to enabling separation, it also has multiple types of flexible members with different lengths.
By exchanging the pair of flexible members, the coil can be brought into close contact with the subject even when the size of the subject changes.

[0013]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 9. FIG. 1 is a perspective view showing the external appearance of one configuration example of the flexible QD coil of the present invention. QD shown here
The coil is for a vertical magnetic field system, and is roughly composed of rigid parts 50a and 50b and flexible parts 60a and 60b, and two coil systems are incorporated inside. The two coil system is a solenoid coil system 100.
And a saddle type coil system 200. Each of these coil systems has a thickness of about 0.5 mm and is on a resin-made coil sheet 70 having a flexibility to be wound around a desired imaging site. Is formed in. The rigid portions 50a and 50b are provided at two positions on the coil sheet 70. The rigid parts 50a, 50b are provided at the portions where the two coil systems intersect, and are fixed to the support plates 51a, 51b fixed to the surface of the coil sheet 70 where no coil is formed.
And a cover 5 which is detachably attached to these support plates 51a and 51b and protects the intersection of the two coil systems.
2a and 52b. The rigid part 50
The coils a and 50b may be formed directly on the support plates 51a and 51b instead of on the coil sheet 70.

Next, the two coil systems will be described.
As described above, the two coil systems are composed of the solenoid coil system 100 and the saddle type coil system 200, but they are really formed as coils when the connectors at both ends of the coil sheet 70 are fitted together. Is. First, the structure of the saddle type coil system 200 will be described. Saddle type coil system 200
The saddle type coils 210 and 220 form a pair.
The saddle type coil 210 is composed of conductive members, for example, coil members 211, 212, 213 and 214 made of copper plates, three printed boards 251, a printed board 261, and a capacitor (described later). Then, the saddle type coil 22
0 is a coil member 221, 222, which is also made of a copper plate,
223, 224, 225, 213, the printed circuit boards 251, 261, a capacitor, two connectors (female) 227, and two connectors (male) 228. The conductive loops of the saddle coil 210 and the saddle coil 220 are formed to have substantially the same length. The printed circuit board 251 is used for joining the coil members, and the printed circuit board 261 among the above-mentioned constituent members.
Are provided for joining the coil members and connecting the signal lines, and the capacitor is provided for lowering the operating voltage of the coil and making it difficult to couple the coil.

Next, the structure of the solenoid coil system 100 will be described. In the present QD coil, the solenoid coil system is composed of one-turn coils arranged in parallel. That is, coil members 111, 112, 113 made of a copper plate similar to a saddle type coil, and printed circuit boards 116, 117 and capacitors (described later) provided at two junction points of the coil members 111, 112, 112, 113.
The solenoid coil system 100 is configured by parallelly connecting two coils of one winding consisting of a connector (male) 118 and a connector (female) 119 provided at the ends of the coil members 111 and 113 with the printed board 116. There is. The connectors 227 and 228 in the present embodiment facilitate the attachment / detachment of the coil to / from the subject. If this is not taken into consideration, the coil sheet 30 may be cylindrical.

Next, details of the configuration will be described. First, the intersection of the saddle type coil system 200 and the solenoid coil system 100 will be described. FIG. 2 shows the details of the intersection of the saddle coil member 225 and the solenoid coil member 111. As described above, in order to reduce the capacitive coupling between the coils, it is necessary to minimize the stray capacitance between the coils in advance. In this embodiment, a copper plate having a predetermined width is used as the coil member, but at the intersection of the coils, both the saddle coil member 225 and the solenoid coil member 111 are formed to have a predetermined width. The gap between these members is set to a predetermined value. As shown in FIG. 3, the interval is, for example, 5 mm or more if the width of the intersecting coil members is 10 mm. As the width of the intersecting coil members becomes wider than that, it is preferable that the distance between them also becomes wider.

Next, the joint portion of each coil member will be described with reference to FIGS. 4 and 5 show details of a joint portion of each coil member of the saddle type coil. As shown in FIG. 4, coil members 211 and 212, and a coil member 224.
And 225 are connected via a coin condenser 260 on the printed circuit board 251. The reason why the printed board 251 is provided is that the coil member is soldered and held so that the coil member does not come off from the coil sheet 70 at the rigid portion when the coil sheet 70 is wound in a tubular shape, and the capacitor 26 is provided.
This is because it is easy to attach 0. Printed circuit board 251
Has four substantially triangular conductive portions 252 each having a portion slightly wider than the coil member, and each coil member and the capacitor 260 are soldered to each conductive portion 252. The other parts are basically joined with the same structure.

Next, the signal output terminal portion of the saddle type coil system 200 will be described. The signal output terminal of the saddle type coil system 200 is a printed circuit board in the rigid portion 50a of FIG.
It is provided in part 261. The details are shown in FIG. Conductive parts 262, 263, 264 are provided on the printed circuit board 261, the coil member 213 is soldered to the conductive part 262, the coil members 212, 225 are soldered to the conductive part 264, and the conductive parts 262 and 263 are electrically connected to each other. A capacitor 270 is connected between the parts 263 and 264, respectively, and
From the conductive portions 263 and 264 to the coil lead wire 271,
272 has been pulled out.

Next, the joints between the coil members of the solenoid coil system 100 and the signal input / output terminal will be described. FIG. 6 shows connection of coil members on the printed circuit board 117 shown in FIG. 4 on the printed circuit board 117
Conductive parts 120 are formed at the points, and the coil members 112 and 113 are soldered to these conductive parts, and the coil members 112 and 113 are connected to each other via the capacitor 160. It is connected. FIG. 7 shows a signal output section of the solenoid coil system 100. The printed circuit board 116 has conductive parts 121, 1 at three locations.
22 and 123 are formed, and the coil members 111 and 112 are soldered to these conductive parts. The conductive members 121 and 122 and the conductive portions 122 and 123 are connected via the capacitor 170. In this way, the two coils are connected in parallel. From the conductive portions 121 and 122, which are the connection points, to the signal lines 171, 17
2 is pulled out.

The QD coil configured as described above is attached to the subject by connecting a connector so that the flexible portion is wound around the subject as shown in FIG. The direction of the coil during this winding is preferably such that the covers 52a and 52b shown in FIG. 1 are on the outside. The reason is that there is a protrusion at the intersection of the two coil systems,
This is because the intimate contact between the subject and the coil is impaired when the raised portion is directed inward. The QD coil according to the present embodiment is not flexible over the entire length (circumferential length) in the radial direction, but is configured by the flexible portions 60a and 60b and the rigid portions 50a and 50b, and therefore is deformed in the radial direction. , And less deformation due to lateral displacement, 2
The orthogonality of the two coil systems can be maintained well. Therefore, the S / N becomes excellent.

Next, a second embodiment of the present invention will be described.
In this second embodiment, the coil shown in FIG.
0a, 50b and the flexible parts 60a, 60b are divided into four parts, and the respective parts are connected by a connector. This will be described below with reference to FIG. In FIG. 9, 500a and 500b are rigid parts,
Reference numerals 600a and 600b are flexible portions. The rigid portion 500a is obtained by cutting the flexible portion 60a connected to the rigid portion 50a shown in FIG. 1 and providing a connector (male) 227 to each coil member at that portion.
Then, the two saddle type coils in the rigid portion 500a are formed symmetrically. The rigid portion 500b is the flexible portion 6 at both ends of the rigid portion 50b shown in FIG.
0a, 60b are cut, and connectors (male) 227 are provided on each coil member at both ends of the cut portions. In this rigid portion 500b as well, it is desirable that the two saddle type coils are formed symmetrically. The flexible portions 600a and 600b are provided with connectors (female) 228 on each coil member at both ends of the remaining flexible portion obtained by cutting the rigid portions 500a and 500b from the coil shown in FIG. In this case, the flexible portions 600a and 600b have the same length. In this embodiment, for one set of rigid parts 500a and 500b,
In addition to one set of flexible 600a and 600b, a plurality of sets of flexible portions having different lengths are prepared. The reason for this is that the flexible part can be replaced in units of groups when the imaged region of the subject is changed, or when the size of the subject is changed even with the same imaged region.

Next, an MRI apparatus using the above QD coil will be described. FIG. 10 is a schematic overall configuration diagram of the MRI apparatus. This MRI apparatus obtains a tomographic image of the subject 1 by utilizing a magnetic resonance (NMR) phenomenon. Therefore, a static magnetic field generating magnet 2 having a necessary and sufficiently large bore diameter and a central processing unit (hereinafter , CPU) 8 and sequencer 7
A transmission system 4, a magnetic field gradient generation system 3, a reception system 5 and a signal processing system 6. The static magnetic field generating magnet 2 generates a uniform magnetic flux in a body space direction or a direction perpendicular to the body space in a predetermined space area in which the subject 1 can be housed. A normal conduction type or superconducting type magnetic field generating means is arranged. The sequencer 7 operates under the control of the CPU 8 and sends various commands necessary for collecting tomographic image data of the subject 1 to the transmission system 4, the gradient magnetic field system 3 and the reception system 5. The transmission system 4 includes a high frequency oscillator 11, a modulator 12, and a high frequency amplifier 1.
3 and the transmitting side high frequency coil 14a, and outputs the high frequency pulse output from the high frequency oscillator 11 to the sequencer 7
In accordance with the command of 1., the modulator 12 amplitude-modulates, the amplitude-modulated high-frequency pulse is amplified by the high-frequency amplifier 13, and then supplied to the high-frequency coil 14a arranged in proximity to the subject 1, whereby the electromagnetic wave is The sample 1 is irradiated. The magnetic field gradient generation system 4 has X, Y,
It comprises a gradient magnetic field coil 9 wound in three directions of Z and a gradient magnetic field power source 10 for driving each coil, and by driving the gradient magnetic field power source 10 of each coil in accordance with a command from the sequencer 7, X, The gradient magnetic fields Gx, Gy, Gz in the three directions of Y and Z are applied to the subject 1. Depending on how the gradient magnetic field is applied, the subject 1
The slice plane for can be set. The reception system 5 includes a reception side high frequency coil (QD coil) 14b, an amplifier 15, a signal synthesizer 26, a quadrature phase detector 16, and an A / D converter.
The high frequency coil 1 on the transmission side, which includes the D converter 17
An electromagnetic wave (NMR signal) of the response of the subject due to the electromagnetic wave emitted from 4a is detected by the high-frequency coil 14b arranged close to the subject 1, and the amplifier 15 and the signal synthesizer 26 are provided.
Also, it is input to the A / D converter 17 via the quadrature detector 16 and converted into a digital amount to obtain two series of collected data, and the signal thereof is sent to the signal processing system 6. The signal processing system 6 includes a CPU 8 and a magnetic disk 18
And a recording device such as a magnetic tape 19 and a display 20 such as a CRT.
Processing such as correction coefficient calculation and image reconstruction is performed, and a signal intensity distribution of an arbitrary cross section or a distribution obtained by performing an appropriate calculation on a plurality of signals is imaged and displayed on the display 20. In FIG. 10, the high frequency coils 14 a and 14 b on the transmitting side and the receiving side and the gradient magnetic field coil 10 are arranged in the magnetic field space of the static magnetic field generating magnet 2.

FIG. 11 shows a part of the circuit diagram of the receiving system 5 using the receiving QD coil of this embodiment for the MRI apparatus.
In FIG. 11, an arrow H indicates the direction of the static magnetic field, and for this static magnetic field H, the solenoid coil system 10 of the QD coil is
0 and saddle coil system 200 are arranged as shown. The NMR signal of the nuclear spin in the subject 1 which has caused a resonance phenomenon due to the electromagnetic wave from the transmission side high frequency coil 14 a of the transmission system 4 is received by the solenoid coil system 100 and the saddle coil system 200. At this time, a signal having a phase difference of 90 ° is induced in the solenoid coil system 100 and the saddle coil system 200. Then, the output signals of these coil systems are amplified by the amplifiers 15a and 15b. The signal of the saddle coil system 200 is output with a 90 ° phase shift through the phase shifter 27 in the signal synthesizer 26, and the signal of the solenoid coil system 100 is output by the attenuator 2.
8, the signal is output after being leveled with the signal of the saddle coil system 200. These two signals are added by the adder 29 and output as a signal twice the output signal of the saddle coil system. Then, the signal is input to the CPU 8 via the quadrature detector 16 and the A / D converter 17 shown in FIG. 10, and the image is reconstructed.

According to the present invention, two systems of coils are provided on a flexible coil holding member so that the receiving directions thereof are orthogonal to each other, and when the flexible member is formed into a cylindrical shape, the degree of freedom of deformation thereof is reduced. Therefore, a rigid part is provided for that purpose. However, it is desirable to consider the deformation of the flexible portion in the direction of both edges.
As a measure against this, it is conceivable that the rigidity of the flexible member itself in the length direction (direction orthogonal to the circumference) of the cylinder is made larger than that in the circumferential direction. As a possible method in this case, a reinforcing member is fixed to the flexible member, or the flexible member itself is made of a fibrous composite member and the number of fibers in the length direction of the cylinder is made larger than the number in the circumferential direction. and so on.

[0025]

According to the present invention described above, the following effects are brought about. That is, according to the first aspect of the invention, since the receiving QD coil of the MRI apparatus can be formed in a cylindrical shape in the arrangement direction by arranging the flexible portion and the rigid portion, Adhesion of the coil to the subject is improved, and the rigid portion reduces the degree of freedom for strain deformation of the coil, so that the orthogonality of the coil is maintained and the S / N can be improved.
According to the second aspect of the present invention, the coil holding member is formed in a band shape, and both ends of the coil holding member can be connected and disconnected by the connector, so that the adhesion of the coil to the subject is improved. It becomes easy to put on and take off. According to the third aspect of the present invention, since the intersecting portion of the two coil systems including the solenoid coil and the saddle type coil is provided in the rigid portion, deformation of the coil holding member at the intersecting portion is small.
For this reason, no deformation coupling occurs in the two coil systems at the intersection. According to the invention as set forth in claim 4, since the coil member interval is secured at 5 mm or more at the intersection of the coils of the two systems, the influence of the coupling of the coils of the two systems does not appear. According to the invention described in claim 5, since the rigid portion and the flexible portion are divided to enable connector connection and a plurality of flexible portions having different lengths are provided, the size of the subject may change, If the size of the imaged part changes, it can be dealt with by exchanging the flexible part. The sensitivity distribution of the coil is lower near the center of the coil and higher near the coil. Therefore, the S / N ratio is best when there is no clearance between the coil and the subject.
Is good. Therefore, for that purpose, it is desirable that the coil has a shape that conforms to the shape of the subject, but the shape of the subject is very different and it is not possible to cope with it without flexibility. By providing flexibility, the shape of the subject can be freely adjusted, so that the S / N can be improved.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing details of an intersecting portion of a solenoid coil and a saddle coil of the QD coil shown in FIG.

FIG. 3 is a sectional view taken along the line AA ′ in FIG.

FIG. 4 is a perspective view showing joining of coil members in a rigid portion of the saddle type coil of FIG.

5 is a perspective view showing a signal output terminal portion of the saddle type coil of FIG. 1. FIG.

6 is a perspective view showing joining of coil members of the solenoid coil of FIG. 1. FIG.

FIG. 7 is a perspective view showing a signal output terminal portion of the solenoid coil of FIG.

8 is a perspective view showing a state when the QD coil of FIG. 1 is attached to a subject.

FIG. 9 is a perspective view of a QD coil according to another embodiment of the present invention.

FIG. 10 is a block diagram showing the configuration of an MIR device using the QD coil of the present invention.

FIG. 11 is a block diagram showing a configuration example of a QD coil receiving circuit of the present invention.

[Explanation of symbols]

 50a rigid part 50b rigid part 51a supporting plate 51b supporting plate 60a flexible part 60b flexible part 70 coil sheet 100 solenoid coil system 111 solenoid coil member 112 solenoid coil member 113 solenoid coil member 116 printed circuit board 117 printed circuit board 200 saddle type coil system 211 saddle Type coil member 212 saddle type coil member 213 saddle type coil member 214 saddle type coil member 221 saddle type coil member 222 saddle type coil member 223 saddle type coil member 224 saddle type coil member 225 saddle type coil member 251 printed circuit board 261 printed circuit board

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[Procedure amendment]

[Submission date] July 17, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title: Receiver coil for MRI apparatus

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving coil of a magnetic resonance imaging apparatus (hereinafter, referred to as an MRI apparatus), and more particularly to a receiving coil having flexibility which can be closely attached to a subject.

[0002]

BACKGROUND OF THE INVENTION MRI apparatus,-out location to the strong uniform static magnetic field space to form the subject static magnetic field generating magnet according to a predetermined pulse sequence, the RF magnetic field and gradient magnetic field is applied to the subject, the subject where magnetic resonance nuclear spins of the constant cross section (hereinafter, referred to as NMR.) phenomenon to cause a, the results generated by detecting a NMR signal, a tomographic image by the image reconstructed by the two-dimensional Fourier transform method or the like detection signal Is displayed. The detection of the NMR signal is performed by disposing a high-frequency receiving coil in the vicinity of the subject, but conventionally, a pair of coils, for example, a solenoid coil or a saddle type coil is used to receive the unidirectional NMR signal. methods and, in order to improve the S / N, a method for receiving two-way NMR signals two coils system are perpendicular sensitivity directions is adopted.
Coil of the latter case, two reception directions of the coil system each other
Since they are orthogonal to each other, QD (Quardrature Detection)
It is called a coil.

Conventional QD coils include a saddle type coil and a saddle type coil for the horizontal magnetic field type, and a solenoid coil and a saddle type coil for the vertical magnetic field type. Proposed. M
The sensitivity of the receiving coil in the RI apparatus is improved as the coil is closely attached to the subject, and thus the S / N is also improved.
The conventional QD coil described above is manufactured by winding a coil around a bobbin made of resin and having poor flexibility. For this reason, it is difficult to bring the coil into close contact with the subject, and the sensitivity and S / N cannot be said to be so excellent.

[0004]

In order to bring the coil into close contact with the subject and to improve the sensitivity and S / N of the coil, it is necessary to give flexibility to the coil portion. However, if the coil is made flexible, in the case of the QD coil, a coupling (coupling) between two coil systems occurs, which becomes a problem. If the coupling, a current of high-frequency current to one coil system, a high frequency electric to the other coil system
It is said that the flow leaks, but the factor that causes the coupling is that the distance between the intersecting parts of each coil system is close to several mm. For the coupling, capacitive coupling by stray capacitance,
Inductive coupling, which couples to the other side by the magnetic flux generated by one coil system, is considered. Inductive coupling can be adjusted by placing a good conductor, such as a copper plate, near the coil system to balance the magnetic flux. Further, the capacitive coupling cannot be adjusted by this method, but it can be dealt with by making the stray capacitance between the coil systems as small as possible in advance. However, such adjustment and correspondence can be made with the precondition that the shape of each coil system is constant.

If the QD coil is made to have flexibility, the QD coil has a large degree of freedom of deformation and is easily deformed. When deformed, the magnetic flux balance is largely lost and the coupling becomes large. Coupling of the coils means that the other side is a load on each coil, and the S / N of the detection is lowered, and the image is deteriorated. Due to the above problems, a flexible receiving QD coil for an MRI apparatus has not been realized.

An object of the present invention is to solve the above-mentioned problems, to provide a flexible QD coil for reception of an MRI apparatus, and to provide a QD coil capable of coping with a change in the size of a subject. To do.

[0007]

In order to achieve the above object, the present invention provides a receiving coil for an MRI apparatus which is mounted on a subject and detects a magnetic resonance signal, wherein the receiving direction is orthogonal to the static magnetic field direction, and Two coil systems whose reception directions are orthogonal to each other are arranged in a coil holding member which is formed by alternately arranging a non-conductive flexible part and a non-conductive rigid part, and which can be formed in a tubular shape in the arranging direction. It is provided (Claim 1). Further, the present invention achieves the object by forming a coil holding member in a band shape in the above coil and providing connectors for connecting and disconnecting each of the two coil systems at both ends of the coil holding member. (Claim 2). Furthermore,
The present invention, in the coil, the two coil systems with a solenoid-type coil, the saddle coils perpendicular to the solenoidal coil, the purpose to form a cross section of the solenoid coil and the saddle coils in the rigid portion (Claim 3). Further, the present invention achieves the object by intersecting each coil member at the intersection of the solenoid type coil and the saddle type coil with an interval of at least 5 mm (claim 4).

Further, in order to achieve the above object, the present invention is an MR which is mounted on a subject to detect a magnetic resonance signal.
In the receiver coil for the apparatus I, a coil holding member in which a pair of non-conductive and rectangular rigid members and a pair of non-conductive and rectangular flexible portions are arranged to face each other, and a receiving direction to the coil holding member is a static magnetic field direction. Two coil systems which are orthogonal to each other and whose reception directions are orthogonal to each other are provided, and the coil system has a structure in which each member of the coil holding member can be connected or disconnected by a connector, and a coil member and a connector are provided. The above-mentioned pair of flexible members are provided in plural types having different lengths.

[0009]

In the invention according to claim 1, the coil holding member in which two coil systems whose receiving directions are orthogonal to the static magnetic field direction and whose receiving directions are orthogonal to each other is a flexible portion. And rigid portions are alternately arranged, and can be formed in a cylindrical shape in the arrangement direction. The flexible portion of the coil holding member has the function of facilitating close contact of the coil with the subject when the coil is wound around the subject, and the rigid portion limits the degree of freedom of coil deformation. Therefore, by setting the lengths of the flexible portion and the rigid portion to be appropriate lengths according to the region to be imaged, a QD coil with good performance can be obtained.

According to the second aspect of the present invention, the connectors provided at both ends of the coil holding member formed in the shape of a band are mounted on the imaging site such that the coil cannot be fitted onto the subject in a fitting manner. To facilitate.

In the third aspect of the present invention, the intersection of the solenoid type coil and the saddle type coil of the two coil systems is provided in the rigid portion. Coupling of two coil systems occurs. By providing the intersecting portion in the rigid portion, deformation is less likely to occur. In the invention of claim 4, the coupling is prevented by setting the interval between the coil members where the two coil systems intersect at 5 mm or more.

In the invention according to claim 5 , the rigid member and the flexible member are divided into two pairs , each member is separated, two coil systems are arranged in each member, and they are connected by a connector. Alternatively, it is possible to separate it, and there are multiple types of pairs of flexible members with different lengths, but if the pairs of flexible members are exchanged, the coil will be brought into close contact with the subject even when the size of the subject changes. I will get it.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a perspective view showing the external appearance of one configuration example of the flexible QD coil of the present invention. The QD coil shown here is for a vertical magnetic field system and is roughly classified into rigid parts 50a and 50b and flexible parts 60a and 60b.
And two coil systems are incorporated inside. The two coil system is the solenoid coil system 1
00 and a saddle type coil system 200. Each of these coil systems has a thickness of about 0.5 mm and is made of a resin having a length that allows it to be wound around a desired imaging region of a subject . It is formed on the coil sheet 70. Then, the rigid portions 50a and 50b are provided at two locations on the coil sheet 70.
Is provided. In this embodiment, the rigid portion 50a,
50b is provided in a portion where the two coil systems intersect
There is. The rigid parts 50a and 50b are the coil sheet 70.
Support plate 51 which is a coil fixed to the surface not et provided
a and 51b, and covers 52a and 52b that are detachably attached to these support plates 51a and 51b and that protect the intersections of the two coil systems. The coils of the rigid parts 50a and 50b may be formed directly on the support plates 51a and 51b instead of on the coil sheet 70.

Next, the two coil systems will be described.
Two coil systems, as described above, consists of a solenoid coil system 100 and saddle coil system 200. they real
At this time , the coil is formed when the connectors provided at both ends of the coil sheet 70 are fitted. First, the structure of the saddle type coil system 200 will be described. The saddle coil system 200 is composed of a pair of coils 210 and 220.
Has been. One coil 210 constituting the saddle type coil system 200 includes a coil member 211, 212, 213 , 214 made of a conductive member such as a copper plate, three printed boards 251, a printed board 261, and a capacitor (described later). ) And. Then, the saddle type coil system 200
The other coil 220 to be constructed is a coil member 221, 222, 223, 224, 22 which is also made of a copper plate.
5, 213, the printed circuit boards 251, 261; a capacitor; two connectors (female) 227; and two connectors (male) 228. And coil 2
The conductive loops of 10 and the coil 220 are formed to have substantially the same length. Among the above-mentioned components, the printed circuit board 251 is for joining the coil members, the printed circuit board 261 is for joining the coil members and the connection of the signal line , and the capacitor is the operating voltage of the coil. It is provided to lower the coil and make it difficult to couple the coil.

Next, the structure of the solenoid coil system 100 will be described. In this embodiment , the solenoid coil system is
It consists of two one-turn coils arranged in parallel. That is, coil members 111 , 112 , 113 made of a copper plate similar to a coil member of a saddle type coil system, printed circuit boards 116, 117 and capacitors provided at two junction points of the coil members 111 , 112 , 112 , 113. Two coils of one turn consisting of (described later), a connector (male) 118 and a connector (female) 119 provided at the ends of the coil members 111 and 113 are connected in parallel on the printed circuit board 116 to form the solenoid coil system 100. It is configured. Incidentally, the connector 227 and 228 of the present embodiment, in order to facilitate attaching and detaching the coil to the subject, if not put it into consideration, and the coil sheet 30 into a cylindrical shape, co
The coil members may be connected without providing a connector .

Next, the two coil systems 100, 200
The details of the configuration will be described. First, saddle type coil system 2
00 and the solenoid coil system 100 will be described. FIG. 2 shows the coil member 22 of the saddle type coil system 200.
5 shows the details of the intersection of 5 and the coil member 111 of the solenoid coil system 100 . As described above, in order to reduce the capacitive coupling between the coils, it is necessary to minimize the stray capacitance between the coils in advance. In this embodiment, a copper plate having a predetermined width is used as the coil member, but the saddle type coil system 20 is used at the intersection of the coils.
0 coil member 225 and solenoid coil system 100
The widths of both the louver member 111 and the ill member 111 are narrowed to a predetermined width, and the distance between these members is set to a predetermined value. As shown in FIG. 3, the interval is, for example, 5 mm or more if the width of the intersecting coil members is 10 mm.
As the width of the intersecting coil members becomes wider,
It is good to make the interval wide.

Next, the joint portion of each coil member will be described with reference to FIGS. 4 and 5 show a saddle type coil system 20.
The details of the joint portion of each coil member of No. 0 are shown. As shown in FIG. 4, the coil members 211 and 212, and the coil members 224 and 225 are connected on the printed circuit board 251 via capacitors 260, respectively. Printed circuit board 251
The reason for providing is that when the coil sheet 70 is wound in a tubular shape, the coil member is soldered and held so as not to come off from the coil sheet 70 at the rigid portion, and the capacitor 260 is easily attached. .. The printed circuit board 251 has four substantially triangular conductive portions (print patterns) 252 each having a portion slightly wider than the coil member.
The coil member and the capacitor 260 are soldered to the conductive portions 252, respectively. The other parts are basically joined with the same structure.

Next, the signal output terminal portion of the saddle type coil system 200 will be described. The signal output terminal of the saddle type coil system 200 is a printed circuit board in the rigid portion 50a of FIG.
It is provided in part 261. The details are shown in FIG. Conductive parts 262, 263, 264 are provided on the printed circuit board 261, the coil member 213 is soldered to the conductive part 262, the coil members 212, 225 are soldered to the conductive part 264, and the conductive parts 262 and 263 are electrically connected to each other. A capacitor 270 is connected between the parts 263 and 264, respectively, and
From the conductive parts 263 and 264 to the coil lead wire (signal
(Line) 271, 272 are drawn out.

Next, the joints between the coil members of the solenoid coil system 100 and the signal input / output terminal will be described. FIG. 6 shows connection of coil members on the printed circuit board 117 shown in FIG. 4 on the printed circuit board 117
Conductive parts 120 are formed at the points, and the coil members 112 and 113 are soldered to these conductive parts, and the coil members 112 and 113 are connected to each other via the capacitor 160. It is connected. FIG. 7 shows a signal output section of the solenoid coil system 100. The printed circuit board 116 has conductive parts 121, 1 at three locations.
22 and 123 are formed, and the coil members 111 and 112 are soldered to these conductive parts. The conductive members 121 and 122 and the conductive portions 122 and 123 are connected via the capacitor 170. In this way, the two coils are connected in parallel. Lead wires ( signal wires ) from the conductive parts 121 and 122 that are the connection points
171, 172 are pulled out.

The QD coil configured as described above is attached to the subject by connecting a connector so that the flexible portion is wound around the subject as shown in FIG. The direction of the coil during this winding is preferably such that the covers 52a and 52b shown in FIG. 1 are on the outside. The reason is that there is a protrusion at the intersection of the two coil systems 100 and 200 , and if the protrusion is directed inward, the close contact between the subject and the coil will be impaired. The QD coil according to the present embodiment is not flexible over the entire length (peripheral length) in the circumferential direction when it is formed into a tubular shape, but the flexible portions 60a and 60b and the rigid portions 50a and 50b.
Since it is composed of and, while allowing deformation in the radial direction ,
The deformation that impairs the orthogonality of the two coil systems in the sensitivity direction is small, the adhesion to the subject is good, and the orthogonality of the two coil systems can be kept good. Therefore, the S / N becomes excellent.

Next, a second embodiment of the present invention will be described.
In this second embodiment, the coil shown in FIG.
0a, 50b and the flexible parts 60a, 60b are divided into four parts, and the respective parts are connected by a connector. This embodiment will be described below with reference to FIG. In FIG. 9, 500a and 500b are rigid parts, and 600a and 600b are flexible parts. The rigid portion 500a is the rigid portion 50a shown in FIG.
The flexible portion 60a connected to is cut and the connector (male) 227 is provided on each portion of the flexible portion 60a. The pair of coils forming the saddle type coil system in the rigid portion 500a are formed symmetrically. The rigid portion 500b is the rigid portion 50 shown in FIG.
The flexible parts 60a and 60b at both ends of b are cut, and connectors (male) 227 are provided on each coil member at both ends of the cut parts. In this rigid portion 500b as well, it is desirable that the pair of coils forming the saddle type coil system be formed symmetrically. Flexible parts 600a, 6
00b is one in which connectors (female) 228 are provided on each coil member at both ends of the remaining flexible portion obtained by cutting the rigid portions 500a and 500b from the coil shown in FIG. In this case, the flexible parts 600a and 6
00b has the same length. In this embodiment, a plurality of sets of flexible parts having different lengths are prepared in addition to one set of flexible parts 600a and 600b for one set of rigid parts 500a and 500b. The reason for this is that the flexible part can be replaced in units of groups when the imaged region of the subject is changed, or when the size of the subject is changed even with the same imaged region.

Next, an MRI apparatus using the above QD coil will be described. FIG. 10 is a schematic overall configuration diagram of the MRI apparatus. This MRI apparatus obtains a tomographic image of the subject 1 by utilizing a magnetic resonance (NMR) phenomenon. Therefore, a static magnetic field generating magnet 2 having a necessary and sufficiently large bore diameter and a central processing unit (hereinafter , CPU) 8 and sequencer 7
A transmission system 4, a magnetic field gradient generation system 3, a reception system 5 and a signal processing system 6. The static magnetic field generating magnet 2 is for generating a uniform static magnetic field in a predetermined space area capable of accommodating the subject 1 in the body axis direction or in a direction perpendicular to the body axis, and is a permanent magnet system around the space area. Alternatively, a normal conducting type or superconducting type magnetic field generating means is arranged. The sequencer 7 operates under the control of the CPU 8 and sends various commands necessary for collecting tomographic image data of the subject 1 to the transmission system 4, the gradient magnetic field system 3 and the reception system 5. The transmission system 4 includes a high frequency oscillator 11, a modulator 12, a high frequency amplifier 13, and a transmission side high frequency coil 14a. The high frequency pulse output from the high frequency oscillator 11 is transmitted by the modulator 12 according to a command from the sequencer 7. Amplitude modulation, the amplitude-modulated high-frequency pulse is amplified by the high-frequency amplifier 13, and then the high-frequency coil 14a is arranged in the vicinity of the subject 1.
Is supplied to the subject 1, so that the subject 1 is irradiated with the electromagnetic wave. The magnetic field gradient generation system 4 is X,
It is composed of a gradient magnetic field coil 9 wound in three directions of Y and Z and a gradient magnetic field power source 10 for driving each coil, and by driving the gradient magnetic field power source 10 of each coil according to an instruction from the sequencer 7, The gradient magnetic fields Gx, Gy, Gz in the three directions of X, Y, Z are applied to the subject 1. The slice plane for the subject 1 can be set by the method of applying the gradient magnetic field. The receiving system 5 includes a receiving side high frequency coil (QD coil) 14b.
An amplifier 15, a signal synthesizer 26, a quadrature detector 16 and an A / D converter 17, and the electromagnetic wave (NMR signal) of the response of the object by the electromagnetic wave emitted from the high frequency coil 14a on the transmitting side is detected. The A / D converter 17 is detected by the high-frequency coil 14b arranged close to the sample 1, and passes through the amplifier 15, the signal synthesizer 26, and the quadrature phase detector 16.
Is input to, converted into a digital amount, converted into two series of collected data, and the signal thereof is sent to the signal processing system 6. The signal processing system 6 is composed of a CPU 8, a recording device such as a magnetic disk 18 and a magnetic tape 19, and a display 20 such as a CRT. The CPU 8 performs processing such as Fourier transform, correction coefficient calculation, image reconstruction, etc. The signal intensity distribution of the cross section or the distribution obtained by performing an appropriate calculation on a plurality of signals is imaged and displayed on the display 20. In FIG. 10, the high frequency coils 14 a and 14 b on the transmitting side and the receiving side and the gradient magnetic field coil 10 are arranged in the magnetic field space of the static magnetic field generating magnet 2.

FIG. 11 shows a part of the circuit diagram of the receiving system 5 using the receiving QD coil of this embodiment for the MRI apparatus.
In FIG. 11, an arrow H indicates the direction of the static magnetic field, and for this static magnetic field H, the solenoid coil system 10 of the QD coil is
0 and saddle coil system 200 are arranged as shown. The NMR signal of the nuclear spin in the subject 1 which has caused a resonance phenomenon due to the electromagnetic wave from the transmission side high frequency coil 14 a of the transmission system 4 is received by the solenoid coil system 100 and the saddle coil system 200. At this time, a signal having a phase difference of 90 ° is induced in the solenoid coil system 100 and the saddle coil system 200. Then, the output signals of these coil systems are amplified by the amplifiers 15a and 15b. So
Signal solenoids coil system 100 is outputted by shifting the phase by 90 degrees through a phase shifter 27 in the signal combiner 26, also signals of saddle coil system 200 attenuator 2
8, the signal is level-matched with the signal of the solenoid coil system 100 and output. These two signals are the adder 2
It is added at 9 and output. The signal is shown in FIG.
Is input to the CPU 8 via the quadrature detector 16 and the A / D converter 17 shown in FIG.

According to the present invention, two systems of coils are provided on a flexible coil holding member so that the receiving directions thereof are orthogonal to each other, and when the flexible member is formed into a cylindrical shape, the degree of freedom of deformation thereof is reduced. Therefore, a rigid part is provided for that purpose. However, it is desirable to consider so that the flexible portion is unlikely to be deformed such that the diameters on both edges are changed . As a measure against this, it is conceivable that the rigidity of the flexible member itself in the length direction (direction orthogonal to the circumference) of the cylinder is made larger than that in the circumferential direction. As a possible method in this case, a reinforcing member is fixed to the flexible member, or the flexible member itself is made of a fibrous composite member and the number of fibers in the length direction of the cylinder is made larger than the number in the circumferential direction. and so on.

[0025]

According to the present invention described above, the following effects are brought about. That is, according to the first aspect of the invention, the receiving QD coil of the MRI apparatus can be formed by alternately arranging the flexible portions and the rigid portions and forming a cylindrical shape in the arrangement direction. The portion improves the adhesion of the coil to the subject, and the rigid portion reduces the degree of freedom with respect to strain deformation of the coil, so that the orthogonality of the coil is maintained and the S / N can be improved. According to the second aspect of the present invention, the coil holding member is formed in a band shape, and both ends of the coil holding member can be connected and disconnected by the connector, so that the adhesion of the coil to the subject is improved. It becomes easy to put on and take off. According to the third aspect of the present invention, since the intersecting portion of the two coil systems including the solenoid coil and the saddle type coil is provided in the rigid portion, deformation of the coil holding member at the intersecting portion is small. For this reason, no deformation coupling occurs in the two coil systems at the intersection. According to the invention as set forth in claim 4, since the coil member interval is secured at 5 mm or more at the intersection of the coils of the two systems, the influence of the coupling of the coils of the two systems does not appear. According to the invention described in claim 5, since the rigid portion and the flexible portion are divided to enable connector connection and a plurality of flexible portions having different lengths are provided, the size of the subject may change, If the size of the imaged part changes, it can be dealt with by exchanging the flexible part.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing details of an intersecting portion of a solenoid coil and a saddle coil of the QD coil shown in FIG.

FIG. 3 is a sectional view taken along the line AA ′ in FIG.

FIG. 4 is a perspective view showing joining of coil members in a rigid portion of the saddle type coil of FIG.

5 is a perspective view showing a signal output terminal portion of the saddle type coil of FIG. 1. FIG.

6 is a perspective view showing joining of coil members of the solenoid coil of FIG. 1. FIG.

FIG. 7 is a perspective view showing a signal output terminal portion of the solenoid coil of FIG.

8 is a perspective view showing a state when the QD coil of FIG. 1 is attached to a subject.

FIG. 9 is a perspective view of a QD coil according to another embodiment of the present invention.

FIG. 10 is a block diagram showing the configuration of an MIR device using the QD coil of the present invention.

FIG. 11 is a block diagram showing a configuration example of a QD coil receiving circuit of the present invention.

[Description of Reference Signs] 50a Rigid part 50b Rigid part 51a Support plate 51b Support plate 60a Flexible part 60b Flexible part 70 Coil sheet 100 Solenoid coil system 111 Solenoid coil member 112 Solenoid coil member 113 Solenoid coil member 116 Printed circuit board 117 Printed board 200 Saddle Type coil system 211 saddle type coil member 212 saddle type coil member 213 saddle type coil member 214 saddle type coil member 221 saddle type coil member 222 saddle type coil member 223 saddle type coil member 224 saddle type coil member 225 saddle type coil member 251 print Board 261 printed circuit board

Claims (5)

[Claims] 1. A receiving coil for an MRI apparatus mounted on a subject for detecting a magnetic resonance signal, comprising two sets of coil systems in which a receiving direction is orthogonal to a static magnetic field direction and the receiving directions are orthogonal to each other. A receiving coil for an MRI apparatus, characterized in that it is formed by arranging a conductive flexible portion and a non-conductive rigid portion, and is arranged on a coil holding member that can be formed in a cylindrical shape in the arrangement direction. 2. The receiving coil for an MRI apparatus according to claim 1, wherein the coil holding member is formed in a band shape, and both ends of the coil holding member connect and disconnect each of the two coil systems. M is provided with
Receiver coil for RI equipment. 3. The receiving coil for an MRI apparatus according to claim 1 or 2, wherein the two coil systems include a solenoid type coil and a pair of saddle type coils orthogonal to the solenoid type coil. An M is characterized in that an intersection of the coil and the saddle type coil is formed in the rigid portion.
Receiver coil for RI equipment. 4. The receiving coil for an MRI apparatus according to claim 3, wherein each coil member at the intersecting portion of the solenoid type coil and the saddle type coil intersects at an interval of at least 5 mm. Receiver coil. 5. A receiver coil for an MRI apparatus, which is mounted on a subject to detect a magnetic resonance signal, comprising a pair of non-conductive rectangular rigid members and non-conductive rectangular flexible members facing each other. A coil holding member and two sets of coil systems whose receiving direction is orthogonal to the static magnetic field direction and whose receiving directions are orthogonal to each other are provided to the coil holding member, and the coil system is provided with a connector at each part of the coil holding member. A receiving coil for an MRI apparatus, comprising a pair of flexible members having a structure capable of connection or disconnection and having a coil member and a connector and having different lengths.