A passive auxiliary resonator

Abstract

The application discloses a passive auxiliary resonator and relates to the technical field of medical apparatuses, which comprises a resonant cage structure, a slotted end cover and a spacing field suppressor, one end of the resonant cage structure is connected with the slotted end cover, the other end is open, and a plurality of spacing field suppressors are uniformly distributed along the circumference of the resonant cage structure, the resonant cage structure is used for being sleeved in a birdcage coil of a nuclear magnetic resonance device, and the resonant cage structure is provided with different size models according to the size of a cross-sectional area. The passive auxiliary resonator in the embodiment is placed in a nuclear magnetic resonance cabin for use, can realize substantial enhancement of the radio frequency magnetic field strength in the resonator, and further improves the nuclear magnetic resonance imaging resolution; meanwhile, the radio frequency magnetic field in the resonator is uniformly distributed, so that the imaging quality in the cavity remains consistent with the change of positions; the overall structure does not need to be additionally connected with cables, and the size can be selected and used according to needs, so as to adapt to the nuclear magnetic resonance imaging enhancement of different sizes of human body parts.

Description

Technical Field

[0001] This invention relates to the technical field of medical devices, and in particular to a passive auxiliary resonator. Background Technology

[0002] Magnetic resonance imaging (MRI) is widely used in clinical diagnosis, and its spatial resolution is positively correlated with the intensity of the radiofrequency magnetic field within the MRI scanner. For local anatomical regions of the human body, standalone MRI scanners are often limited by insufficient internal radiofrequency magnetic field strength, making it difficult to achieve high spatial resolution imaging of these regions. While existing small-diameter passive resonators can locally enhance the radiofrequency magnetic field, they are only applicable to extremely small-radius local anatomical regions such as the wrist. Existing resonators used in the head or chest offer limited enhancement due to their increased radius, and the field strength inhomogeneity within the resonant region becomes significant with increasing radius. Furthermore, the ineffective gap magnetic field between these existing resonators and the MRI scanner is not controlled, resulting in inefficient use of this energy. Many MRI enhancement schemes also require external coaxial cables or matching circuits, increasing equipment complexity and scan preparation time. Summary of the Invention

[0003] The purpose of this invention is to provide a passive auxiliary resonator to solve the problems existing in the prior art, thereby significantly enhancing and uniformly distributing the radio frequency magnetic field strength within the resonator, and thus improving the resolution of nuclear magnetic resonance imaging.

[0004] To achieve the above objectives, the present invention provides the following solution:

[0005] This invention provides a passive auxiliary resonator, comprising a resonant cage structure, a slotted end cap, and spacer field suppressors. One end of the resonant cage structure is connected to the slotted end cap, and the other end is open. Several spacer field suppressors are evenly distributed along the circumference of the resonant cage structure. The slotted end cap and the spacer field suppressors work together to concentrate the radio frequency magnetic field within the cavity of the resonant cage structure, thereby enhancing the intensity of the radio frequency magnetic field within the cavity. The resonant cage structure is used to be fitted inside the birdcage coil of a nuclear magnetic resonance (NMR) device. The resonant cage structure is available in different sizes depending on its cross-sectional area.

[0006] Preferably, the resonant cage structure includes resonant strips and resonant end rings. A pair of resonant end rings are provided, and a plurality of resonant strips are evenly distributed between the two resonant end rings. The resonant strips are arranged along the line connecting the centers of the two resonant end rings to form a cylindrical cage.

[0007] Preferably, both the resonant strip and the resonant end ring include a metal body and a surface layer, the surface layer covering the surface of the metal body, and the surface layer is a dielectric material.

[0008] Preferably, the inner diameter of the resonant end ring is at least 120 mm, and the length of the resonant strip is at least 200 mm.

[0009] Preferably, the slotted end cap includes an end cap plate and radial grooves, and the end cap plate is provided with a plurality of radial grooves along the radial direction.

[0010] Preferably, the number of radial grooves is the same as the number of resonant strips in the resonant cage structure, and the radial grooves divide the slotted end cap into several sector plates.

[0011] Preferably, the width of the radial groove of the slotted end cap is 1mm-3mm.

[0012] Preferably, the slotted end cap is a metal cover plate.

[0013] Preferably, the spacer field suppressor includes a plurality of metal plates evenly distributed along the circumference of the resonant cage structure. The metal plates are inserted into the support cylinder at equal intervals. The support cylinder is sleeved in the inner cavity of the nuclear magnetic resonance device, and the metal plate array is perpendicular to the radio frequency magnetic field direction between the nuclear magnetic resonance device and the resonant cage structure.

[0014] Preferably, the metal sheet is rectangular and has a thickness of 0.5mm-2mm.

[0015] Preferably, the metal sheet is inserted into the resonant strip of the resonant end ring, or the metal sheet is connected to the nuclear magnetic resonance device, and the metal sheet array is perpendicular to the direction of the interval radio frequency magnetic field between the nuclear magnetic resonance device and the resonant cage structure.

[0016] The present invention achieves the following technical effects compared to the prior art:

[0017] This invention employs a passive auxiliary resonator placed within an MRI chamber, which significantly enhances the intensity of the radio frequency magnetic field within the resonator, thereby improving the resolution of MRI imaging. Simultaneously, the uniform distribution of the radio frequency magnetic field within the resonator ensures consistent imaging quality regardless of position. The resonant cage structure, slotted end caps, and spacer field suppressor work synergistically to enhance the radio frequency magnetic field intensity within the resonator chamber by at least 100%, with radial non-uniformity below 5%. The overall structure requires no additional cable connections, and its dimensions can be selected as needed to accommodate MRI enhancement of different sized body parts. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the installation structure of the passive auxiliary resonator in an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the passive auxiliary resonator in an embodiment of the present invention. Figure 1 .

[0021] Figure 3 This is a schematic diagram of the passive auxiliary resonator in an embodiment of the present invention. Figure 2 .

[0022] Figure 4 This is a schematic diagram of the resonant cage structure in an embodiment of the present invention.

[0023] Figure 5 This is a schematic diagram of the spacer field suppressor in an embodiment of the present invention.

[0024] Figure 6 This is a schematic diagram of the structure in an embodiment of the present invention.

[0025] Figure 7 This is a schematic diagram of the slotted end cap in an embodiment of the present invention.

[0026] Figure 8 This is a schematic diagram of the layered structure of the resonant strip and resonant end ring in an embodiment of the present invention.

[0027] Figure 9 This is a simulation diagram of the radial magnetic field strength of the passive auxiliary resonator in an embodiment of the present invention.

[0028] Figure 10 This is a simulation diagram of the axial magnetic field strength of the spacer field suppressor in an embodiment of the present invention.

[0029] Figure 11 This is a schematic diagram of the resonant frequency of the passive auxiliary resonator support cylinder in an embodiment of the present invention.

[0030] Figure 12 This is a schematic diagram of the axial direction radio frequency magnetic field strength of the passive auxiliary resonator in an embodiment of the present invention.

[0031] Figure 13 This is a schematic diagram of the radial direction radio frequency magnetic field strength of the passive auxiliary resonator in an embodiment of the present invention.

[0032] In the diagram: 1-Resonant cage structure, 2-Slotted end cap, 3-Metal sheet, 4-Birdcage coil, 5-Resonant strip, 6-Resonant end ring, 7-Metal body, 8-Surface layer, 9-Support cylinder. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] It should be noted that in the description of this invention, the terms "upper," "lower," "left," "right," "inner," "outer," "front," "rear," "clockwise," and "counterclockwise," etc., indicating directional or positional relationships, are based on the directional or positional relationships shown in the accompanying drawings. These are merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," "third," and "fourth" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly defined.

[0035] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] The purpose of this invention is to provide a passive auxiliary resonator to solve the problems existing in the prior art, so as to significantly enhance and uniformly distribute the radio frequency magnetic field strength in the resonator, thereby improving the resolution of nuclear magnetic resonance imaging.

[0037] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] like Figures 1 to 13As shown, this embodiment provides a passive auxiliary resonator, including a resonant cage structure 1, a slotted end cap 2, and spacer field suppressors. One end of the resonant cage structure 1 is connected to the slotted end cap 2, and the other end is open. Several spacer field suppressors are evenly distributed along the circumference of the resonant cage structure 1. The resonant cage structure 1 is used to be fitted inside the birdcage coil 4 of the nuclear magnetic resonance device. The resonant cage structure 1 is available in different sizes according to its cross-sectional area. In this embodiment, the slotted end cap 2 and the spacer field suppressors are used to compensate for the magnetic field inside the cavity and suppress the radio frequency magnetic field in other regions, further enhancing the radio frequency magnetic field strength inside the cylindrical resonant structure. The passive auxiliary resonator of this embodiment is placed inside the MRI chamber and can significantly enhance the intensity of the radio frequency magnetic field inside the resonator, thereby improving the resolution of MRI imaging. At the same time, the radio frequency magnetic field inside the resonator is uniformly distributed, so that the imaging quality inside the cavity remains consistent with the position. The overall structure can work as an auxiliary device without the need for an additional power supply cable, and the size can be selected as needed to adapt to the MRI imaging enhancement of different sized human body parts. The birdcage coil 4 is used to simulate the birdcage coil 4 of the clinical MRI equipment and is used to provide the radio frequency magnetic field excitation source.

[0039] As an optional solution, in this embodiment, the resonant cage structure 1 includes resonant strips 5 and resonant end rings 6. A pair of resonant end rings 6 are provided, and several resonant strips 5 are evenly distributed between the two resonant end rings 6. The resonant strips 5 are arranged parallel to the line connecting the centers of the two resonant end rings 6, forming a cylindrical cage. In this embodiment, the resonant cage structure 1 can be equivalent to an LC resonant circuit. When the resonant cage structure 1 is working, the radio frequency magnetic field excited by the birdcage coil 4 can first resonate in this cylindrical resonant cage structure 1. The results of the radio frequency magnetic field strength in the radial and axial directions of the cross-section are as follows: Figure 9 , Figure 10As shown. Compared to the standalone birdcage coil 4, the central radio frequency magnetic field strength has been enhanced. However, to accommodate the relatively large anatomical region of the human body, the enhancement of the central radio frequency magnetic field gradually weakens as the diameter of the resonant cage structure 1 increases. Furthermore, since the anatomical region of the human body is only located within the cylindrical resonant structure, the radio frequency magnetic fields in other areas (such as the area between the resonant cage structure 1 and the birdcage coil 4, and the outer side of the bottom of the resonant cage structure 1) are ineffective and do not aid in imaging. In this embodiment, a passive auxiliary resonator is placed at the center of the birdcage coil 4; the birdcage coil 4 is excited using two orthogonally placed 1A current sources with a 90° phase difference, allowing the radio frequency magnetic field excited by the birdcage coil 4 to resonate first within the resonant cage structure 1. The slotted end cap 2 and the spacer field suppressor are used to suppress the radio frequency magnetic field in other areas and further enhance the radio frequency magnetic field strength inside the cylindrical resonant structure; the passive auxiliary resonator resonates at a frequency of approximately 64MHz within the birdcage coil 4, corresponding to a clinical MRI device with a static magnetic field strength of 1.5T. Currently, the most common MRI machines in clinical practice are 1.5T and 3.0T, with resonant frequencies of 64MHz and 128MHz, respectively. The resonant frequency can be determined according to physical formulas. For example, if this embodiment is used for a 1.5T MRI machine, the resonant frequency of the passive auxiliary resonator needs to be 64MHz to match the hospital's MRI machine. By changing the size of the passive auxiliary resonator in this embodiment, its operating resonant frequency can be adjusted.

[0040] As an alternative, both the resonant strip 5 and the resonant end ring 6 include a metal body 7 and a surface layer 8. The surface layer 8 covers the surface of the metal body 7 and is made of a dielectric material. The dielectric material can be Rogers RO4003C, conductive plastic (such as carbon black-filled polyethylene), or PCB material.

[0041] As an optional embodiment, the inner diameter of the resonant end ring 6 is at least 120 mm, and the length of the resonant strip 5 is at least 200 mm. In this embodiment, the inner diameter of the resonant cage structure 1 is 130 mm, and the length exceeds 217 mm. The relevant dimensions can be adjusted according to the size of the body parts to be accommodated, so as to fully accommodate complete limbs such as hands, waist, and head. The dimensions of the resonant cage structure 1, the slotted end cap 2, and the spacer field suppressor are adjustable to adapt to the magnetic resonance imaging enhancement of human body parts of different sizes, or to adapt to the use of a low magnetic field (such as 1.5 T) much smaller than that of conventional micro-MRI for high-resolution micro-MRI of the whole body of animals of different sizes.

[0042] As an optional solution, in this embodiment, the slotted end cap 2 includes an end cap plate and radial slots, with several radial slots arranged along the radial direction on the end cap plate. In this embodiment, the radial slots suppress additional surface eddy currents caused by the rapid switching magnetic field; the slotted end cap 2 enhances the magnetic field strength in the central region, weakening the ineffective radio frequency magnetic field on the outer side of the bottom of the resonant cage structure 1. The results of the radio frequency magnetic field strength in the radial direction (along the diameter direction) and axial direction (along the length direction) of the cross-section of the passive auxiliary resonator are as follows: Figure 6 , Figure 7 As shown.

[0043] As an optional solution, in this embodiment, the number of radial slots is the same as the number of resonant strips 5 in the resonant cage structure 1. The radial slots divide the slotted end cap 2 into several fan-shaped plates. In this embodiment, the radius of the slotted end cap 2 is equal to the radius of the resonant cage structure 1, the length of the field-isolating suppressor is equal to that of the resonant cage structure 1, and the width is slightly smaller than the gap width between the birdcage coil 4 and the resonant cage structure 1. The radius of the slotted end cap 2 is equal to the radius of the resonant cage structure 1, which just encapsulates the end cap at the end of the resonant cage structure 1. The length of the field-isolating suppressor is equal to that of the resonant cage structure 1, ensuring complete suppression of the magnetic field around the resonator.

[0044] As an optional solution, in this embodiment, the width of the radial groove of the slotted end cap 2 is 1mm-3mm, preferably 1-2mm, to avoid energy leakage. In this embodiment, the slotted end cap 2 preferably has a plurality of radial grooves arranged along the axial direction. The slotted end cap 2 generates a compensating magnetic field through induced current to enhance the radio frequency magnetic field and suppress eddy currents.

[0045] As an optional solution, in this embodiment, the slotted end cap 2 is a metal cover plate, preferably a copper plate.

[0046] As an alternative, in this embodiment, the spacer field suppressor includes several metal plates 3, which are evenly distributed along the circumference of the resonant cage structure 1 to ensure uniform separation of the magnetic field.

[0047] As an optional solution, in this embodiment, the metal sheet 3 is rectangular and has a thickness of 0.5mm-2mm. The metal sheet 3 is preferably a copper sheet, and the specific size can be varied according to the requirements.

[0048] As an optional solution, in this embodiment, the metal sheet 3 can be inserted into the resonant strip 5 of the resonant end ring 6, or the metal sheet 3 can be connected to the nuclear magnetic resonance equipment. The array of metal sheets 3 is perpendicular to the direction of the interval radio frequency magnetic field between the nuclear magnetic resonance equipment and the resonant cage structure. In some embodiments, the slotted end cap 2 is close to the bottom of the resonant cage structure 1 and in contact with it; the interval field suppressor can be placed on the outside of the resonant cage structure 1 without contact and maintaining a certain interval distance. In this embodiment, the birdcage coil 4 in the nuclear magnetic resonance equipment will generate an alternating current, which will in turn generate a change in the magnetic field. The change in the magnetic field will cause a change in the current of the resonant cage structure 1 and generate a magnetic field, which will then be superimposed and enhanced with the magnetic field generated by the birdcage coil 4 to form a magnetic field ring. The metal plate blocks and concentrates the magnetic field in the middle, thereby enhancing the magnetic field strength of the monitoring area. In this embodiment, the metal sheet 3 is not in contact with the resonant cage structure 1. The metal sheet 3 is inserted into the support cylinder 9 at equal intervals to support and position the metal sheet 3 and the resonant cage structure 1. The support cylinder 9 is sleeved and installed in the inner cavity of the nuclear magnetic resonance equipment. The support cylinder 9 can be a ring of non-magnetic material similar to airform, in which metal sheets 3 can be inserted at equal intervals to form a circular cylinder; the foam support cylinder 9 can contact the resonator and magnetic resonance machine in the middle and be placed directly in the magnetic resonance cavity (in front of the head of the bed).

[0049] In this embodiment, during MRI scanning, the passive auxiliary resonator uses the clinical MRI birdcage coil 4 as the excitation source of the radio frequency magnetic field, generating resonance within the auxiliary resonator. The slotted end cap 2 and the spacer field suppressor work together to concentrate the resonant magnetic field at the center of the resonator cavity, significantly increasing the field strength within the cavity and thus improving the imaging signal-to-noise ratio and spatial resolution. Simultaneously, the radio frequency magnetic field distribution within the resonant cage structure 1 is uniform, ensuring consistent imaging quality regardless of position. The resonator requires no additional cable connections and can be fabricated using a thin copper layer and a low-loss integrated circuit board (containing no stainless steel or other ferromagnetic materials), making it suitable for high-resolution MRI examinations of anatomical areas such as the hand.

[0050] In this embodiment, the radio frequency magnetic field of a clinical MRI machine can resonate within the passive auxiliary resonator, enhancing the intensity of the radio frequency magnetic field in that region and ensuring its uniform intensity distribution. This results in MRI scans with high imaging resolution and high spatial uniformity. This embodiment is based on a large-aperture cylindrical resonant structure design, sufficient to accommodate anatomical regions of the human body such as the hand, or the entire animal body. Furthermore, the large-aperture cylindrical resonant structure, in conjunction with the slotted end cap 2 and the spacer field suppressor, achieves high-gain and uniform radio frequency magnetic field enhancement without the need for external cables or additional tuning networks.

[0051] This embodiment provides a method for using a passive auxiliary resonator and its imaging principle, as detailed below:

[0052] like Figures 1 to 13As shown, as part of the passive auxiliary resonator, the spacer field suppressor consists of an array of multiple copper sheets parallel to the axis, placed between the cylindrical resonant structure and the birdcage coil 4. Since the radio frequency magnetic field excited by the birdcage coil 4 is a circularly polarized magnetic field, according to the boundary conditions of an ideal metal:

[0053] ,

[0054] in, B is the normal vector; B is the magnetic field, and to suppress the magnetic field, the metal should be perpendicular to the direction of the magnetic field. Therefore, the copper sheet of the spacer field suppressor is designed to be perpendicular to the tangential component of the circularly polarized magnetic field between the cylindrical resonant structure and the birdcage coil 4. In this embodiment, the results of the radio frequency magnetic field strength in the radial and axial directions of the passive auxiliary resonator are as follows: Figure 9 , Figure 10 As shown.

[0055] Compared to a standalone birdcage coil 4 (in clinical MRI equipment), the central radio frequency magnetic field strength, enhanced with a passive auxiliary resonator, is twice as strong, with radial non-uniformity less than 5%. This is because the signal-to-noise ratio (SNR) in MRI is proportional to the radio frequency magnetic field strength of the receiving coil. :

[0056] ,

[0057] in, It is the intensity of the radio frequency emission magnetic field. P abs For the coil to absorb power, γ τ is the gyromagnetic ratio of water molecules and the pulse duration; therefore, the signal-to-noise ratio of the imaging system equipped with a passive auxiliary resonator is also enhanced to twice that of a clinical MRI machine used alone.

[0058] This embodiment can expand the size of the anatomical region that can be accommodated by selecting the aperture of the passive auxiliary resonator. This application can also be extended to clinical MRI equipment with different static magnetic field strengths by adjusting other dimensional parameters of the passive auxiliary resonator, such as the resonator's radius, length, thickness of the resonant strip 5, and width of the resonant end ring 6.

[0059] In clinical imaging, the MRI machine excites a radiofrequency magnetic field inside the birdcage coil 4 for imaging. However, due to the large radius of the birdcage coil 4, the radiofrequency magnetic field strength at the center is weak, resulting in a low signal-to-noise ratio and affecting imaging resolution. Placing a [missing information - likely a device or device] inside the birdcage coil... Figure 1 After the passive auxiliary resonator shown, the radio frequency magnetic field excited by the birdcage coil resonates in the passive auxiliary resonator, and the resonant frequency is equal to the desired Larmor frequency (e.g., Figure 11As shown in the diagram, this significantly enhances the magnetic field at the center compared to a single birdcage coil 4. Simultaneously, the radio frequency magnetic field distribution within the resonator is uniform, ensuring consistent imaging quality across the cavity regardless of position. The resonator, composed of dielectric and metallic materials, possesses its own equivalent inductance and equivalent capacitance, the specific values ​​of which depend on the resonator's structure and dimensions (which have been adjusted in this embodiment).

[0060] The working principle of the passive auxiliary resonator in this embodiment is as follows:

[0061] In nuclear magnetic resonance (NMR), the birdcage coil, through the coordinated operation of multiple conductors, forms a uniform radio frequency magnetic field (B1 field) within the coil. The birdcage coil generates a changing magnetic field due to alternating current. This magnetic field variation causes a change in current in the resonant cage structure 1, generating its own magnetic field. This magnetic field then superimposes and enhances the magnetic field generated by the birdcage coil, forming a magnetic field loop. The metal plate blocks and concentrates the magnetic field in the center, further strengthening the magnetic field intensity in the monitored area. The resonant cage structure 1 has its own resonant frequency. Resonance occurs when its own resonant frequency equals the frequency of the external radio frequency magnetic field (the birdcage coil in NMR).

[0062] The simulated resonant frequency obtained using the passive auxiliary resonator described above is as follows: Figure 11 As shown, the results of the radio frequency magnetic field strength in the radial and axial directions of the cross-section are as follows: Figure 9 , Figure 10 As shown in the figure. The results show that, under no-load conditions (no human anatomical tissue), the central radio frequency magnetic field strength equipped with the passive auxiliary resonator is enhanced to approximately twice the original strength, with radial non-uniformity less than 5%, and the normalized radial length within the range of [-0.5, 0.5]; the normalized axial length within the range of [-0.5, 0.5], with better magnetic field strength enhancement closer to the axial center of the birdcage. By adjusting the size or other parameters of the passive auxiliary resonator, the resonant frequency can be adjusted as needed to adapt to the Larmor frequency of different MRI systems. Simultaneously, the aperture of the resonant cage structure 1 can be selected according to appropriate size and model to adapt to MRI enhancement of different sized human body parts. This embodiment can also be applied to small animal magnetic resonance imaging (micro-MRI), adapting to different sized animals to perform high-resolution micro-MRI of the whole body using a low magnetic field (e.g., 1.5T) much smaller than that of conventional animal micro-MRI.

[0063] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "this embodiment," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with the described embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0064] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A passive auxiliary resonator, characterized in that: The device includes a resonant cage structure, a slotted end cap, and spacer field suppressors. One end of the resonant cage structure is connected to the slotted end cap, and the other end is open. Several spacer field suppressors are evenly distributed along the circumference of the resonant cage structure. The slotted end cap and the spacer field suppressors work together to concentrate the radio frequency magnetic field within the cavity of the resonant cage structure, thereby enhancing the intensity of the radio frequency magnetic field within the cavity. The resonant cage structure is used to be fitted inside the birdcage coil of the nuclear magnetic resonance equipment. The resonant cage structure is available in different sizes according to the cross-sectional area. The resonant cage structure includes resonant strips and resonant end rings. A pair of resonant end rings are provided, and several resonant strips are evenly distributed between the two resonant end rings. The resonant strips are arranged along the line connecting the centers of the two resonant end rings to form a cylindrical cage. The slotted end cap includes an end cap plate and radial grooves, and the end cap plate is provided with a plurality of radial grooves along the radial direction; The number of radial grooves is the same as the number of resonant strips in the resonant cage structure. The radial grooves divide the slotted end cap into several sector plates. The width of the radial grooves in the slotted end cap is 1mm-3mm. The spacer field suppressor includes several metal plates evenly distributed along the circumference of the resonant cage structure. The metal plates are inserted into the support cylinder at equal intervals. The support cylinder is sleeved in the inner cavity of the nuclear magnetic resonance device, and the metal plate array is perpendicular to the radio frequency magnetic field direction between the nuclear magnetic resonance device and the resonant cage structure.

2. The passive auxiliary resonator according to claim 1, characterized in that: Both the resonant strip and the resonant end ring include a metal body and a surface layer, the surface layer covering the surface of the metal body, and the surface layer is a dielectric material.

3. The passive auxiliary resonator according to claim 1, characterized in that: The inner diameter of the resonant end ring is at least 120 mm, and the length of the resonant strip is at least 200 mm.

4. The passive auxiliary resonator according to claim 1, characterized in that: The slotted end cap is a metal cover plate.

5. The passive auxiliary resonator according to claim 1, characterized in that: The metal sheet is rectangular and has a thickness of 0.5mm-2mm.

6. The passive auxiliary resonator according to claim 1, characterized in that: The metal sheet is inserted into the resonant strip of the resonant end ring, or the metal sheet is connected to the nuclear magnetic resonance device, and the metal sheet array is perpendicular to the direction of the interval radio frequency magnetic field between the nuclear magnetic resonance device and the resonant cage structure.

Images