Passive coil and coil device applying same

Abstract

The utility model discloses a passive coil, which comprises a coil base material, a coil, a conductor material and at least one group of series combination A formed by an inductor La and two PIN diodes Va which are reversely connected in parallel, and the series combination A is connected in parallel with a decoupling capacitor Ca and then is connected in series with a bridging capacitor C through the conductor material to form an annular ring or a rectangular ring; by optimizing the layout through the passive coil, the higher signal-to-noise ratio and image resolution of the local region of interest are improved, and by means of the mode, the device can improve the accuracy and reliability of magnetic resonance imaging and has important practical significance and clinical application value.

Description

Technical Field

[0001] The utility model relates to the technical field of magnetic resonance imaging, and more specifically, to a passive coil and an application coil device thereof. Background Art

[0002] Existing magnetic resonance imaging (MRI) systems use wired coil devices for imaging. The disadvantages of wired coils include coupling loss, positioning restrictions, size restrictions, etc. Wired coils can cause coupling loss due to impedance mismatch between the coil and the preamplifier, thereby reducing the signal-to-noise ratio (SNR) of the MRI system. The cable length limits the coverage and accessibility of wired coils. Wired coils tend to have a large size and weight because they include multiple accessories such as connectors, preamplifiers, baluns, and plugs, which may increase the power consumption and heat dissipation of the MRI system and increase patient discomfort.

[0003] A magnetic resonance imaging system usually includes a cavity-type superconducting magnet, a gradient coil surrounding the superconducting magnet, a cavity-type body coil located within the gradient coil, an examination table top on which the patient is placed, and a local coil used to cover a certain part of the patient, such as a knee coil, shoulder coil, spine coil, wrist coil, body coil, head and neck coil, etc.

[0004] By exciting the tissues containing hydrogen atoms in the human body, a weak radio frequency signal is generated, which is then received by an induction coil and processed by a computer to reconstruct the internal structural image of the human body. The imaging process of magnetic resonance imaging includes steps such as external magnetic field, radio frequency excitation, signal detection, spatial positioning and image reconstruction. When the human body is placed in the magnetic resonance imaging device, the hydrogen nuclei in the human body will be affected by the strong magnetic field, and the disordered arrangement will change to an ordered arrangement, parallel or anti-parallel to the direction of the magnetic field, forming a macroscopic magnetization vector. When a radio frequency pulse of a certain frequency is applied to the human body, if the frequency is the same as the precession frequency of the hydrogen nuclei, energy transfer will occur, causing the hydrogen nuclei to transition from a low energy level to a high energy level (i.e., nuclear magnetic resonance). At the same time, the macroscopic magnetization vector will deviate from its original direction to form a transverse magnetization vector. When the radio frequency pulse stops, the hydrogen nuclei will gradually return to their original energy state and direction (i.e., relaxation). During the relaxation process, the hydrogen nuclei will release weak radio frequency signals, which can be detected by the induction coil and converted into electrical signals. In order to distinguish signals from different positions, it is necessary to add a gradient magnetic field to the main magnetic field so that the magnetic field strength changes linearly along the spatial coordinate axis, so that the hydrogen nuclei at different positions have different precession frequencies. By adjusting the direction and strength of the gradient magnetic field, the signal can be spatially encoded. By performing mathematical analysis of the signal (such as Fourier transform), the frequency and amplitude of the signal can be obtained to determine the spatial position and intensity of the signal. The intensity of the signal is related to the density and relaxation time of the hydrogen nuclei, and the signal intensity of different tissues varies greatly. According to the intensity of the signal, it can be converted into black and white grayscale to reconstruct the image of the human body, and an accurate three-dimensional image of the inside of the object can be drawn based on this.

[0005] At present, there is an increasing demand for scanning of the carotid artery, knees, shoulders, spine, wrists, body, etc. in magnetic resonance applications. For existing bilateral coils, the two cables connected to the two sides of the carotid coil generally need to be combined in front of the neck or chest of the subject to form a cable and then connected to the magnetic resonance imaging equipment. This setting method results in a longer cable line and requires an RF choke to suppress common mode current, resulting in the coil cable being bulky and having poor bending resistance. In addition, the cable and RF choke are less comfortable when pressed on the patient. In particular, most carotid coils are not soft enough and cannot fit the surface curvature of the carotid artery well, so the signal-to-noise ratio is not good enough, and patients experience poor comfort during scanning. Utility Model Content

[0006] The utility model provides a passive coil and an application coil device thereof, which have a higher signal-to-noise ratio (SNR) and image resolution (Resolution) in a local area of ​​interest and a simpler arrangement.

[0007] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0008] A passive coil, comprising:

[0009] The coil substrate is a flat material made of a flexible and magnetic resonance compatible electrical insulating material for attaching and fixing the coil;

[0010] A coil, comprising a conductor material made of copper and coated with an anti-oxidation material on the surface, and

[0011] At least one group consisting of an inductor L a and two anti-parallel PIN diodes V a Series combination A, series combination A is connected in parallel with a decoupling capacitor C a Then connect a cross-over capacitor C in series through the conductor material to form a ring or rectangular coil or any other coil form; or

[0012] It comprises at least two parallel annular rings or two parallel rectangular rings, and the cross-over capacitor C part is replaced by a conductor material and is directly connected.

[0013] The coil layout including at least two parallel annular coils is an axisymmetric layout structure, and the coils overlap each other and the intersection points are interconnected.

[0014] The coil layout including at least two parallel rectangular coils is a diagonal layout structure, forming a coil unit, and the cross-overlapping parts of two or more coil units are insulated from each other.

[0015] Preferably, the coil and the coil substrate are contained in a soft non-magnetic patch package to form a coil patch.

[0016] An application coil device including a coil patch includes: a main magnetic field generator for generating a main magnetic field passing through an imaging area; a radio frequency exciter for applying radio frequency pulses of a certain frequency to a subject to be imaged; and a signal receiver and an imaging display device.

[0017] Two coil patches are bonded opposite to each other on the same center line on both sides of the imaging area. The RF pulse magnetic field signal emitted by the RF exciter passes through at least the plane section where the coil patch is located and then passes through the decoupling circuit to form a conversion signal, which is then received by the signal receiver to display the image.

[0018] Preferably, the coil patch can also be used in conjunction with an active or passive head coil.

[0019] It can be seen from the above technical scheme that the background of the utility model is based on an existing cavity-type superconducting magnet, a gradient coil surrounding the superconducting magnet, a cavity-type body coil located in the gradient coil, an examination table bed for placing the patient, and a local coil for covering a certain part of the patient, such as a knee coil, a shoulder coil, a spine coil, a wrist coil, a body coil, and a head and neck coil, etc. Without adding other facilities, the passive coil is optimized in layout to improve the signal-to-noise ratio and image resolution of the local area of ​​interest. In this way, the device can improve the accuracy and reliability of magnetic resonance imaging, which has important practical significance and clinical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the layout of a single toroidal coil;

[0021] Figure 2 It is a schematic diagram of the layout of a single rectangular coil;

[0022] Figure 3 It is a schematic diagram of the double toroidal coil layout;

[0023] Figure 4 This is another layout diagram of a double toroidal coil;

[0024] Figure 5 It is a schematic diagram of the double rectangular coil layout;

[0025] Figure 6 It is a schematic diagram of the superimposed layout of three toroidal coils;

[0026] Figure 7 This is a schematic diagram of the superimposed layout of four toroidal coils;

[0027] Figure 8 It is a schematic diagram of the layout of four rectangular coils stacked together;

[0028] Fig. 9 It is a schematic diagram of the application scenario of the utility model. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the utility model clearer, the technical solutions in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments.

[0030] Embodiment 1

[0031] like Figure 1 The passive coil shown in FIG. 1 includes an inductor L a 1 and two anti-parallel PIN diodes V a2 Series combination A, series combination A is connected in parallel with a decoupling capacitor C a 3 and then a jumper capacitor C4 is connected in series through the conductor material 5 to form a ring.

[0032] like Figure 2 A passive coil is shown, comprising an inductor L a 11 and two anti-parallel PIN diodes V a 21 series combination B, series combination B is connected in parallel with a decoupling capacitor C a 31 and then connected in series with a jumper capacitor C41 through the conductor material 51 to form a rectangular loop.

[0033] Embodiment 2

[0034] like Figure 3 or Figure 4 A passive coil is shown, comprising an inductor L a 1 and two anti-parallel PIN diodes V a 2 Series combination A, series combination A is connected in parallel with a decoupling capacitor C a 3 and then connected in series through the conductor material 4 to form a first annular ring,

[0035] Also includes an inductor L b 12 and two anti-parallel PIN diodes V b 22 series combination D, series combination D is connected in parallel with a decoupling capacitor C b 32 and then connected in series through the conductor material 42 to form a second annular ring.

[0036] The first annular ring and the second annular ring are symmetrically cross-overlaid, the intersections are interconnected, and the inductors or decoupling capacitors are distributed away from the intersections, forming a shape similar to an "8".

[0037] like Figure 5 A passive coil is shown, comprising an inductor L a 11 and two anti-parallel PIN diodes V a 21 series combination B, series combination B is connected in parallel with a decoupling capacitor C a 31 and then connected in series through the conductor material 41 to form a first rectangular loop,

[0038] Also includes an inductor L b 13 and two anti-parallel PIN diodes V b 23 series combination E, series combination E is connected in parallel with a decoupling capacitor C b 33 and then connected in series through the conductor material 43 to form a second rectangular loop,

[0039] The first rectangular coil and the second rectangular coil are arranged in parallel at the chamfered corners of the rectangular sides, forming a coil unit.

[0040] Embodiment 3

[0041] like Figure 6 The passive coil shown in the figure consists of an inductor L a 1 and two anti-parallel PIN diodes V a 2 Series combination A, series combination A is connected in parallel with a decoupling capacitor C a 3 and then connected in series through the conductor material 4 to form a first annular ring,

[0042] Also includes an inductor L b 12 and two anti-parallel PIN diodes V b 21 Series combination D, series combination D is connected in parallel with a decoupling capacitor C b 31 and then connected in series through the conductor material 41 to form a second annular ring.

[0043] Then include an inductor L c 14 and two anti-parallel PIN diodes V c 24 series combination E, series combination E is connected in parallel with a decoupling capacitor C c 34 and then connected in series through the conductor material 44 to form a third annular ring.

[0044] The first annular ring, the second annular ring and the third annular ring are cross-superimposed in an equilateral triangle symmetry, the intersections are interconnected, and the inductors or decoupling capacitors are distributed away from the intersections.

[0045] Embodiment 4

[0046] like Figure 7 The passive coil shown in the figure consists of an inductor L a 1 and two anti-parallel PIN diodes V a 2 Series combination A, series combination A is connected in parallel with a decoupling capacitor C a 3 and then connected in series through the conductor material 4 to form a first annular ring,

[0047] Also includes an inductor L b 12 and two anti-parallel PIN diodes V b 21 Series combination D, series combination D is connected in parallel with a decoupling capacitor C b 31 and then connected in series through the conductor material 41 to form a second annular ring.

[0048] Then include an inductor L c 14 and two anti-parallel PIN diodes V c 24 series combination E, series combination E is connected in parallel with a decoupling capacitor C c 34 and then connected in series through the conductor material 44 to form a third annular ring.

[0049] It also includes an inductor Ld 15 and two anti-parallel PIN diodes V d 25 series combination F, series combination F connected in parallel with a decoupling capacitor C d 35 and then connected in series through the conductor material 45 to form a fourth annular ring,

[0050] The first annular ring, the second annular ring, the third annular ring and the fourth annular ring are cross-superimposed in an axisymmetric manner, the intersections are interconnected, and the inductors or decoupling capacitors are distributed away from the intersections.

[0051] Embodiment 5

[0052] like Figure 8 A passive coil is shown, comprising an inductor L a 11 and two anti-parallel PIN diodes V a 21 series combination B, series combination B is connected in parallel with a decoupling capacitor C a 31 and then connected in series through the conductor material 41 to form a first rectangular loop,

[0053] Also includes an inductor L b 13 and two anti-parallel PIN diodes V b 23 series combination E, series combination E is connected in parallel with a decoupling capacitor C b 33 and then connected in series through the conductor material to form a second rectangular loop.

[0054] The first rectangular loop and the second rectangular loop are arranged in parallel at the chamfered corners of the rectangular sides, forming a first coil unit;

[0055] It also includes a second coil unit, which has the same layout as the first coil unit. As shown in the figure, the dotted line represents the part, which is used for identification and does not directly reflect the disconnection of the connection relationship.

[0056] The first coil unit and the second coil unit are cross-overlapped and insulated at the cross-overlapping positions, so as to form a passive coil.

[0057] The passive coils described in Examples 1-5 are all contained in a soft non-magnetic patch package, and a coil patch is assembled and used together with a main magnetic field generator, a radio frequency exciter, a signal receiver and an imaging display device.

[0058] Coil Application:

[0059] like Fig. 9 In the application scenario of the carotid artery shown in the figure, two coil patches are bonded opposite to each other on the same center line on both sides of the area to be imaged. The RF pulse magnetic field signal emitted by the RF exciter passes through at least the plane section where the coil patch is located and then passes through the decoupling circuit to form a conversion signal, which is then received by the signal receiver to display the image.

[0060] The coil technology content involved in this application is also applicable to the knees, prostate, thyroid, shoulders and other parts.

[0061] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A passive coil, comprising: The coil substrate is a flat material made of a flexible and magnetic resonance compatible electrical insulating material for attaching and fixing the coil; A coil, comprising a conductor material, and At least one group consisting of an inductor L a and two anti-parallel PIN diodes V a Series combination A, series combination A is connected in parallel with a decoupling capacitor C a Then connect a cross-over capacitor C in series through the conductor material to form a ring or rectangular coil or any other coil form; or It comprises at least two parallel annular rings or two parallel rectangular rings, and the cross-over capacitor C part is replaced by a conductor material and is directly connected.

2. A passive coil according to claim 1, characterized in that: The coil layout including at least two parallel annular coils is an axisymmetric layout structure, and the coils overlap each other and the intersection points are interconnected.

3. A passive coil according to claim 1, characterized in that: The coil layout including at least two parallel rectangular coils is a diagonal layout structure, forming a coil unit, and the cross-overlapping parts of two or more coil units are insulated from each other.

4. A passive coil according to claim 1, characterized in that: The conductor material is made of copper and coated with an anti-oxidation material on the surface.

5. A passive coil according to claim 1, characterized in that: The coil and the coil substrate are contained in a soft non-magnetic patch package to form a coil patch.

6. An application coil device comprising the coil patch according to claim 5, comprising: A main magnetic field generator, used for generating a main magnetic field passing through an imaging region; A radio frequency exciter, used for applying radio frequency pulses of a certain frequency to the imaging body; And a signal receiver and an imaging display device, characterized in that: Two coil patches are bonded opposite to each other on the same center line on both sides of the imaging area. The RF pulse magnetic field signal emitted by the RF exciter passes through at least the plane section where the coil patch is located and then passes through the decoupling circuit to form a conversion signal, which is then received by the signal receiver to display the image.

7. The application coil device according to claim 6, characterized in that: The coil patch can also be used in conjunction with an active or passive head coil.

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