JP5771354B2 - Receiving coil device for magnetic resonance imaging apparatus and magnetic resonance imaging apparatus using the same - Google Patents

Description

  The present invention relates to a magnetic resonance imaging (hereinafter referred to as “MRI”) apparatus, and more particularly to a receiving coil apparatus for a magnetic resonance imaging apparatus.

  An MRI apparatus measures a nuclear magnetic resonance (hereinafter referred to as “NMR”) signal generated by a nuclear spin that constitutes a subject, particularly a human tissue, and two-dimensionally describes the shape and function of the head, abdomen, limbs, etc. Or three-dimensional imaging device. As a high-frequency probe for receiving NMR signals, various receiving coils such as a head coil and an abdominal coil surrounding a region of interest in a human body are used. In order to obtain an image with a high SNR in such an MRI apparatus, it is required to increase the intensity of a signal received from a region of interest of the human body. Since the signal strength increases as the installation position of a loop portion (hereinafter referred to as “element coil”) configured by a conductor that is a signal receiving portion of the receiving coil is closer to the region of interest, for example, in Patent Document 1, the receiving coil is connected to the region of interest. The signal strength was increased by closely contacting the signal.

JP-A-7-59751

  In Patent Document 1, it is described that the geometric relative distance between a pair of coils is changed to bring the receiving coil into close contact with the region of interest. However, like the abdominal receiving coil, the region of interest has the size of the receiving coil. Only a method that is limited to a portion that can be regarded as being closer to a flat surface is described, and a method that completely adheres the receiving coil to a portion with many curved surfaces is not described.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a receiving coil device that can be closely attached to a curved surface portion of a human body and can be easily installed at a desired location on the human body.

In order to achieve the above object, a receiving coil device for a magnetic resonance imaging apparatus of the present invention is a receiving coil device for a magnetic resonance imaging apparatus that detects an NMR signal of a subject placed in a static magnetic field space, and includes at least Two or more independent element coils, one or more element coil holding parts for holding each element coil, and the element coil or the element coil holding part, or both, having an element coil fixing function, The coil holding part can be held in a state where the relative distance between the element coils is adjusted in a plurality of directions, and the element coil has flexibility and can be installed in a curved shape along the curve of the subject. The side where each element coil faces the element coil holding part Oite, characterized in that it is fixed by a fixing band.

  In the receiving coil device for a magnetic resonance imaging apparatus of the present invention, each element coil may be attached to the element coil holding portion with a surface fastener.

  In the receiving coil device for a magnetic resonance imaging apparatus of the present invention, each element coil may be fixed by a fixed band on the side facing the element coil holding portion.

  In the receiving coil device for a magnetic resonance imaging apparatus of the present invention, the element coil may be composed of a plurality of pairs of element coils.

  Furthermore, the magnetic resonance imaging apparatus of the present invention uses the receiving coil apparatus for the magnetic resonance imaging apparatus.

  According to the receiving coil device of the present invention, an element can be easily brought into close contact with a desired portion of a human body including many curved surfaces, and the strength of a received signal can be increased.

The block diagram for demonstrating the whole structure of the MRI apparatus with which this invention is applied. The figure which shows the structure of the 1st Example of the receiving coil of this invention. The figure which shows the structure of the 1st Example of the receiving coil of this invention. The figure which shows operation | movement of the 1st Example of the receiving coil of this invention. The figure which shows the example of installation of the 1st Example of the receiving coil of this invention. The figure which shows the example of installation of the 1st Example of the receiving coil of this invention. The figure which shows the structure of the 2nd Example of the receiving coil of this invention. The figure which shows the structure of the 3rd Example of the receiving coil of this invention.

  Hereinafter, preferred embodiments of the MRI apparatus of the present invention will be described in detail with reference to the accompanying drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments of the invention, and the repetitive description thereof is omitted.

  First, an overall outline of an example of an MRI apparatus to which the present invention is applied will be described with reference to FIG. FIG. 1 is a block diagram showing the overall configuration of an MRI apparatus to which the present invention is applied. This MRI apparatus obtains a tomographic image of a subject using an NMR phenomenon. As shown in FIG. 1, the MRI apparatus includes a static magnetic field generation system 2, a gradient magnetic field generation system 3, a transmission system 5, A reception system 6, a signal processing system 7, a sequencer 4, and a central processing unit (CPU) 8 are provided.

  The static magnetic field generation system 2 generates a uniform static magnetic field in the direction perpendicular to the body axis in the space around the subject 1 if the vertical magnetic field method is used, and in the direction of the body axis if the horizontal magnetic field method is used. Thus, a permanent magnet type, normal conducting type or superconducting type static magnetic field generating source is arranged around the subject 1.

  The gradient magnetic field generation system 3 includes a gradient magnetic field coil 9 that applies a gradient magnetic field in the three-axis directions of X, Y, and Z, which is a coordinate system (static coordinate system) of the MRI apparatus, and a gradient magnetic field that drives each gradient magnetic field coil. Gradient magnetic fields Gx, Gy, Gz are applied in the three axial directions of X, Y, and Z by driving the gradient magnetic field power supply 10 of each coil according to a command from the sequencer 4 described later. . At the time of imaging, a slice direction gradient magnetic field pulse (Gs) is applied in a direction orthogonal to the slice plane (imaging cross section) to set a slice plane for the subject 1, and the remaining two orthogonal to the slice plane and orthogonal to each other A phase encoding direction gradient magnetic field pulse (Gp) and a frequency encoding direction gradient magnetic field pulse (Gf) are applied in one direction, and position information in each direction is encoded into an echo signal.

  The sequencer 4 is a control means that repeatedly applies a high-frequency magnetic field pulse (hereinafter referred to as “RF pulse”) and a gradient magnetic field pulse in a predetermined pulse sequence. The sequencer 4 operates under the control of the CPU 8 and collects tomographic image data of the subject 1. Various commands necessary for the transmission are sent to the transmission system 5, the gradient magnetic field generation system 3, and the reception system 6.

  The transmission system 5 irradiates the subject 1 with RF pulses in order to cause nuclear magnetic resonance to occur in the nuclear spins of the atoms constituting the living tissue of the subject 1, and includes a high-frequency oscillator 11, a modulator 12, and a high-frequency amplifier. 13 and a high frequency coil (transmission coil) 14a on the transmission side. The RF pulse output from the high-frequency oscillator 11 is amplitude-modulated by the modulator 12 at a timing according to a command from the sequencer 4, and the amplitude-modulated RF pulse is amplified by the high-frequency amplifier 13 and then placed close to the subject 1. By supplying to the high frequency coil 14a, the subject 1 is irradiated with the RF pulse.

  The receiving system 6 detects an echo signal (NMR signal) emitted by nuclear magnetic resonance of nuclear spins constituting the biological tissue of the subject 1, and receives a high-frequency coil (receiving coil) 14b on the receiving side and a signal amplifier 15 And a quadrature detector 16 and an A / D converter 17. After the NMR signal of the response of the subject 1 induced by the electromagnetic wave irradiated from the high frequency coil 14a on the transmission side is detected by the high frequency coil 14b arranged close to the subject 1 and amplified by the signal amplifier 15, The signal is divided into two orthogonal signals by the quadrature phase detector 16 at the timing according to the command from the sequencer 4, and each signal is converted into a digital quantity by the A / D converter 17 and sent to the signal processing system 7.

  The signal processing system 7 performs various data processing and display and storage of processing results. The signal processing system 7 includes an external storage device such as an optical disk 19 and a magnetic disk 18, an internal storage device such as a ROM 21 and a RAM 22, and a display including a CRT. With 20. When data from the reception system 6 is input to the CPU 8, the CPU 8 executes processing such as signal processing and image reconstruction, and displays the tomographic image of the subject 1 as a result on the display 20, and an external storage device On the magnetic disk 18 or the like.

  The operation unit 25 inputs various control information of the MRI apparatus and control information of processing performed in the signal processing system 7, and includes a trackball or mouse 23 and a keyboard 24. The operation unit 25 is disposed close to the display 20, and the operator controls various processes of the MRI apparatus interactively through the operation unit 25 while looking at the display 20.

  In FIG. 1, the high-frequency coil 14a and the gradient magnetic field coil 9 on the transmission side are opposed to the subject 1 in the static magnetic field space of the static magnetic field generation system 2 into which the subject 1 is inserted. If the horizontal magnetic field method is used, the subject 1 is installed so as to surround it. The high-frequency coil 14b on the receiving side is installed so as to face or surround the subject 1.

  Currently, the radionuclide to be imaged by the MRI apparatus is a hydrogen nucleus (proton) which is a main constituent material of the subject as widely used in clinical practice. By imaging information on the spatial distribution of proton density and the spatial distribution of relaxation time in the excited state, the form or function of the human head, abdomen, limbs, etc. is imaged two-dimensionally or three-dimensionally.

  Next, the receiving coil device according to the first embodiment of the present invention will be described with reference to FIG. FIG. 2A is a perspective view of the receiving coil device according to the first embodiment, and FIG. 2B is a front view.

  In this embodiment, the receiving coil is affixed to the element coil 101, the element coil 102, and the element coils 101, 102 having a circuit pattern made of a flexible substrate inside a flexible material such as urethane foam. The hook-and-loop fastener 104 includes the hook-and-loop fastener 104, the element coil holding portion 103, and the hook-and-loop fastener 104 attached to the element coil holding portion 103. As shown in FIG. 3, the element coils 101 and 102 are usually connected with a plurality of resonance capacitors 106 in series. However, in FIGS. 2 and 4 and subsequent figures, the capacitor is omitted for simplicity and the element coil has one turn. It is shown as a rectangular coil. The circuit portion of each element coil is configured to be bendable using, for example, copper foil. The outputs of the element coils 101 and 102 are amplified by the amplifier 15 and synthesized in the signal processing system 7.

  The hook-and-loop fastener 104 is a means for fixing the element coils 101 and 102 to the element coil holding portion 103, and can be attached to and detached from the element coil holding portion 103 in a state where the relative distance between the pair of element coils 101 and 102 is changed. It is possible to fix. The element coils 101 and 102 and the element coil holding portion 103 are made of a flexible material such as polyethylene foam, and can be bent. However, it is sufficient that at least one of the element coil and the element coil holding portion can be bent.

  Next, the operation of the first embodiment will be described with reference to FIG. FIG. 4A is a perspective view of a state where the receiving coil device of the first embodiment is bent, and FIG. 4B shows a state where the receiving coil device is in close contact with a region of interest 1 of a human body having a relatively small diameter. FIG. 4 (c) is a diagram showing a state in which the consultation coil device is brought into close contact with a region of interest 1 of a human body having a relatively large diameter.

  In this embodiment, the receiving coil can be installed in such a manner that the region of interest 1 of the human body is tightly sandwiched between the pair of element coils 101, 102 by bending the element coils 101, 102 and the element coil holding portion 103, It is fixed by a fixing band 105 to which a fastener 104 is attached. In addition, in consideration of the size of the region of interest, the pair of element coils 101 and 102 are arranged so that the center of the element coil and the region of interest coincide with each other, for example, a line connecting the element coil center passes through the approximate center of the region of interest. Further, it can be fixed by the hook-and-loop fastener 104 in a state where the relative distance is adjusted. Therefore, the element coil center can be installed in close contact with a portion smaller than the element coils 101 and 102.

FIG. 5 shows an installation example of the receiving coil of the horizontal magnetic field type MRI, FIG. 5 (a) is a perspective view thereof, and FIG. 5 (b) is a view seen from the upper surface. FIG. 6 shows an installation example of a vertical magnetic field MRI receiving coil, FIG. 6A shows a perspective view thereof, and FIG. 6B shows a side view thereof. In the installation example of the horizontal magnetic field type MRI in FIG. 5, the element coil to be paired with the receiving coil 14 b is arranged in close contact with the shoulder or elbow of the subject 1 from above and below, and FIG. In the installation example of the vertical magnetic field method, the element coil that is a pair of the receiving coil 14b is disposed in close contact with the knee of the subject 1 from both sides. That is, the element coils are arranged so that the sensitivity direction is substantially perpendicular to the static magnetic field direction. Incidentally, 2 in the figures the static magnetic field generating system, gradient magnetic field generating system, shows a transmission system, showing a static magnetic field B ₀ is generated by the static magnetic field generating system. Since the element coil and the element coil support part have flexibility, the elbow part and the knee part can be installed in a curved shape along the curve of the human body. With respect to the subject 1 on the bed 107, the receiving coil 14b can be installed at a site such as the knee, the elbow, and the knee, the shoulder, and the elbow in the vertical magnetic field method MRI and the horizontal magnetic field method MRI.

Next, the receiving coil device according to the second embodiment of the present invention will be described with reference to FIG. FIG. 7B is a view of the receiving coil device according to the second embodiment as viewed from above, and FIG. 7A is a cross-sectional view of the element coil holding portion as viewed from the side.
The difference from the first embodiment is that a fixing screw 203 is used to fix the element coils 101 and 102 and the element coil holding portion 201. The fixing screw 203 is made of a non-magnetic material such as glass fiber reinforced nylon. In this embodiment, the element coil holding part 201 is configured to be bendable, and the element coil holding part 201 is provided with a hole for attaching the fixing screw 203 and a guide 202 that does not cause the element coils 101 and 102 to fall off.

Next, the operation of the second embodiment will be described.
The element coils 101 and 102 slide on the element coil holding part 201 along the guide 202 to change the relative distance. By tightening the fixing screw 203, the element coils 101 and 102 and the element coil holding part 201 can be firmly fixed.

  Next, a receiving coil device according to a third embodiment of the present invention will be described with reference to FIG. The difference from the first and second embodiments is that a plurality of pairs of element coils are used. Hereinafter, only different portions will be described, and description of the same portions will be omitted. In this embodiment, the receiving coil is composed of a plurality of element coils 302, 303, 304, and 305, each of which is independently fixed to the element coil holding portion 301 by a surface fastener. The element coil holding part 301 may be configured by detachably connecting the element coil holding parts of the first and second embodiments described above in one direction, or may be configured integrally.

Next, the operation of the third embodiment will be described.
Since the plurality of element coils 302, 303, 304, and 305 can be independently fixed at different relative distances, the element coils 302, 303, 304, and 305 can be installed in close contact with a complicated shape or a wide range of regions of interest.

  As mentioned above, although the Example of this invention was described, this invention is not limited to these shapes and fixing means.

1: subject, 2: static magnetic field generation system, 3: gradient magnetic field generation system, 4: sequencer, 5: transmission system, 6: reception system, 7: signal processing system, 8: central processing unit (CPU), 9: Gradient magnetic field coil, 10: Gradient magnetic field power source, 11: High frequency transmitter, 12: Modulator, 13: High frequency amplifier, 14a: High frequency coil (transmitting coil), 14b: High frequency coil (receiving coil), 15: Signal amplifier, 16 : Quadrature phase detector, 17: A / D converter, 18: Magnetic disk, 19: Optical disk, 20: Display, 21: ROM, 22: RAM, 23: Trackball or mouse, 24: Keyboard, 25: Operation unit , 101: Element coil, 102: Element coil, 103: Element coil holding part, 104: Surface fastener, 105: Fixed band, 106: Resonance capacitor, 107: Bed, 20 1: element coil holding part, 202: guide, 203: fixing screw, 301: element coil holding part, 302: element coil, 303: element coil, 304: element coil, 305: element coil.

Claims (4)

A receiving coil device for a magnetic resonance imaging apparatus for detecting an NMR signal of a subject placed in a static magnetic field space,
At least two or more independent element coils, one or more element coil holding parts for holding the element coils, and an element coil fixing function in the element coil or the element coil holding part or both,
The element coil holding portion can be held in a state in which the relative distance between the element coils is adjusted in a plurality of directions,
The element coil has flexibility, can be installed in a shape along the curve of the subject ,
The receiving coil device for a magnetic resonance imaging apparatus , wherein each element coil is fixed by a fixed band on a side facing the element coil holding portion . The receiving coil device for a magnetic resonance imaging apparatus according to claim 1,
The receiving coil device for a magnetic resonance imaging apparatus, wherein each element coil is attached to the element coil holding portion with a surface fastener. The receiving coil device for a magnetic resonance imaging apparatus according to claim 1 or 2 ,
The receiving coil device for a magnetic resonance imaging apparatus, wherein the element coil includes a plurality of pairs of element coils. A magnetic resonance imaging apparatus using the receiving coil device for a magnetic resonance imaging apparatus according to any one of claims 1 to 3 .

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