Circularly polarized intelligent metamaterial radio frequency intensifier and double-breast magnetic resonance imaging system

Abstract

The invention discloses a circular polarization intelligent metamaterial radio frequency intensifier and a double-breast magnetic resonance imaging system comprising the radio frequency intensifier. Circular polarization enhancement of a radio frequency magnetic field is realized through a single circular polarization intelligent metamaterial radio frequency intensifier instead of two independent linear polarization metamaterial radio frequency intensifiers, and the conductor ring with the opening and the adjustable capacitor are mainly used for enhancing linear polarization of the axial radio frequency magnetic field of the radio frequency coil. Linear polarization enhancement of a transverse radio-frequency magnetic field of the radio-frequency coil is realized by the conductor columns connected to the conductor rings, and the design effectively enhances the strength and the centrality of the radio-frequency magnetic field, so that the imaging signal-to-noise ratio can be remarkably improved. Due to the intelligent and tunable application of the adjustable capacitor, dynamic tuning is realized, the circularly polarized intelligent metamaterial radio frequency intensifiers used in pairs have the capability of flexibly and intelligently switching single-side (single-emulsion) and double-side (double-emulsion) imaging modes, and different clinical requirements are met.

Description

Technical Field

[0001] The present invention belongs to the field of medical diagnosis technology, relates to magnetic resonance imaging technology, and in particular to a circularly polarized intelligent metamaterial radio frequency enhancer for magnetic resonance imaging and a double breast magnetic resonance imaging system. Background Art

[0002] The importance of Magnetic Resonance Imaging (MRI) in lesion imaging cannot be ignored. For example, in breast imaging, the importance of double breast MRI lies in its more comprehensive evaluation capabilities compared to single breast MRI. Bilateral imaging can reveal the symmetry and differences between the two breasts, which helps to detect occult lesions and multifocal tumors, which may be missed in unilateral imaging. In addition, double breast MRI is particularly important in the screening of high-risk patients because it can provide a more comprehensive picture of breast health, thereby optimizing diagnostic and treatment decisions. This comprehensiveness not only increases the chances of early detection of breast cancer, but also provides an important basis for the formulation of personalized treatment plans, making patient management more precise.

[0003] One of the problems facing bilateral breast MRI is the signal-to-noise ratio (SNR). Low SNR may affect the visualization of the tumor and increase the risk of missed or misdiagnosis. In addition, low SNR may make subtle lesions difficult to identify, thus affecting doctors' judgment and treatment decisions. Therefore, improving the SNR of bilateral breast MRI is one of the key challenges to improving its clinical application effect.

[0004] Metamaterials provide a new technical solution for improving the signal-to-noise ratio of double breast MRI. Metamaterials are a class of composite materials that are artificially designed and manufactured. Their structures are usually designed on a subwavelength scale to control the interaction between the material and electromagnetic waves or sound waves. The role of metamaterials in improving the signal-to-noise ratio of breast MRI is mainly reflected in their ability to enhance and focus the radio frequency magnetic field. By focusing the radio frequency magnetic field generated by a large-aperture radio frequency coil, the radio frequency magnetic field is effectively concentrated in the breast area, thereby enhancing signal reception in the area, increasing the signal-to-noise ratio, and thus improving the signal-to-noise ratio. Therefore, metamaterials play a key role in the development of double breast MRI technology.

[0005] At present, there are some metamaterial resonators for double breast MRI, such as ceramic resonators with extremely high dielectric constants and orthogonal coil resonators. These technologies have improved the RF field and signal-to-noise ratio to a certain extent, but there are still limitations. First, although the orthogonal coil resonator can achieve circular polarization and enhance signal reception, its design is complex and usually consists of two linearly polarized resonators. When applied to double breast MRI, this means that a combination of four resonators is needed, which not only increases the complexity of the system, but also brings inconvenience in operation; the process of tuning multiple resonators is relatively difficult, which may lead to inconsistent parameter settings, thus affecting the imaging effect and the accuracy of diagnosis. Although ceramic resonators with extremely high dielectric constants can theoretically improve signal strength and imaging quality, there are many challenges in their actual acquisition and use. High-quality ceramic materials with extremely high dielectric constants are not only expensive, but also generally difficult to obtain, which limits their scope of application; in addition, these ceramic materials have poor thermal stability and are easily affected by temperature changes and performance degradation, and their fragility makes them prone to breakage in actual operation, thus affecting the long-term use and reliability of MRI equipment.

[0006] Another important point is that metamaterials should also be paired during bilateral MRI. However, common breast lesions often only appear on one side of the breast in the early stages. When doctors find suspicious lesions on one side of the patient's breast during bilateral breast examinations, they hope to focus on observing the suspicious lesion for further pathological analysis. However, the essence of the current metamaterial enhancement of the RF magnetic field in the target area is to redistribute the RF energy generated by the body coil in the entire space, thereby focusing the strong RF magnetic field near the body coil on the area of ​​interest. The RF energy generated by the body coil is determined by the excitation power, so using metamaterial resonators on both breasts at the same time will result in a larger area of ​​RF energy focus, thereby weakening the RF energy allocated to a single breast, resulting in a reduction in the signal-to-noise ratio. Therefore, the integrated bilateral metamaterial cannot help MRI focus on lesions on one side of the breast. Summary of the invention

[0007] The purpose of the present invention is to provide a circularly polarized intelligent metamaterial radio frequency enhancer for magnetic resonance imaging and a double breast magnetic resonance imaging system comprising the circularly polarized intelligent metamaterial radio frequency enhancer. The circularly polarized intelligent metamaterial radio frequency enhancer can realize circularly polarized radio frequency magnetic field enhancement and has the ability to switch between unilateral and bilateral breast imaging modes. The material is easy to obtain, the cost is low, the structure is simple, and the performance of double breast MRI can be greatly improved, thereby solving the problems existing in the above-mentioned existing double breast MRI metamaterial resonators.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] The present invention provides a circularly polarized intelligent metamaterial radio frequency enhancer, comprising a hollow cylindrical dielectric substrate, a conductor ring, a conductor connector and an adjustable capacitor, wherein:

[0010] The outer ring of the hollow cylindrical dielectric substrate is sleeved with a plurality of the conductor rings along its axial direction;

[0011] Any one of the conductor rings is provided with an opening in the circumferential direction of the conductor ring, and the adjustable capacitor is arranged in the opening of any one of the conductor rings;

[0012] Any two adjacent conductor rings are electrically connected via the conductor connector.

[0013] In one embodiment, any two adjacent conductor rings are spaced apart in the axial direction of the hollow cylindrical dielectric substrate to form an axial spacing of the guide rings.

[0014] In one embodiment, the axial spacings of all the guide rings are completely identical, completely identical, or not completely identical.

[0015] In one embodiment, the hollow cylindrical dielectric substrate is a cylindrical dielectric substrate or a prismatic dielectric substrate; any one of the conductor rings is a circular ring, an elliptical ring or a polygonal ring.

[0016] In one embodiment, the hollow cylindrical dielectric substrate is a cylindrical dielectric substrate, any one of the conductor rings is a circular ring, and any one of the conductor rings (12) is fixedly mounted on the outside of the hollow cylindrical dielectric substrate (11).

[0017] In one embodiment, any one of the conductor rings is fixed to the outer wall of the hollow cylindrical dielectric substrate by interference fit.

[0018] In one embodiment, two openings are spaced apart on any one of the conductor rings, and the two openings are symmetrically arranged at 180°, and the openings of all the conductor rings are axially aligned.

[0019] In one embodiment, the conductor connecting member is a conductor column, which is parallel to the axial direction of the hollow cylindrical dielectric substrate, and the conductor column sequentially passes through all the conductor rings to achieve connection between any two adjacent conductor rings.

[0020] In one embodiment, two conductor posts are provided, and the two conductor posts are arranged 180° symmetrically, and on the cross section of the cylindrical dielectric substrate, a line connecting the two conductor posts is perpendicular to a line connecting the two columns of openings.

[0021] In one implementation, the adjustable capacitor is a digital capacitor.

[0022] The present invention also proposes a double breast magnetic resonance imaging system, comprising a radio frequency coil and an electromagnetic shielding layer arranged outside the radio frequency coil, and also comprising a pair of circularly polarized smart metamaterial radio frequency enhancers as described in any one of the above items, wherein the pair of circularly polarized smart metamaterial radio frequency enhancers are arranged at intervals in the center of the radio frequency coil, and the axial direction of any one of the circularly polarized smart metamaterial radio frequency enhancers is perpendicular to the axial direction of the radio frequency coil.

[0023] Compared with the prior art, the present invention has achieved the following technical effects:

[0024] The circularly polarized smart metamaterial RF enhancer proposed in the present invention realizes the enhancement of the circular polarization of the integrated RF magnetic field. It realizes the circular polarization enhancement of the RF magnetic field through a single circularly polarized smart metamaterial RF enhancer instead of two separate linearly polarized metamaterial RF enhancers, overcoming the poor effect of the original metamaterial only having linear RF magnetic field enhancement and the cumbersomeness of the multi-coil combination. The conductor ring with an opening and the adjustable capacitor are mainly used to enhance the linear polarization of the axial RF magnetic field of the RF coil, while the linear polarization enhancement of the transverse RF magnetic field of the RF coil is achieved by the conductor column connected to the conductor ring. In addition to having an excellent magnetic field enhancement effect, this simple and unified structure also has the advantages of low manufacturing cost and easy installation. The design of the circularly polarized smart metamaterial RF enhancer effectively enhances the intensity and concentration of the RF magnetic field, thereby significantly improving the imaging signal-to-noise ratio.

[0025] The present invention uses intelligent tunable application of adjustable capacitors, and can adjust the capacitance value of each capacitor through a digital signal to change the resonant frequency of the circularly polarized intelligent metamaterial radio frequency enhancer, so that the circularly polarized intelligent metamaterial radio frequency enhancer is maintained in an optimal resonant mode during use, that is, the resonant frequency is consistent with the Larmor frequency, thereby achieving the highest imaging signal-to-noise ratio gain, and the image quality is best improved, which is beneficial to actual medical diagnosis.

[0026] In addition, the present invention adopts the intelligent tunable technology of adjustable capacitance, so that the circularly polarized intelligent metamaterial radio frequency enhancer used in pairs has the ability to flexibly and intelligently switch between unilateral (single breast) and bilateral (bilateral breast) imaging modes. Specifically, in the bilateral (bilateral breast) imaging mode, the digital capacitance of the bilateral circularly polarized intelligent metamaterial radio frequency enhancer 1 is intelligently adjusted to match the resonant frequency of the bilateral circularly polarized intelligent metamaterial radio frequency enhancer with the Larmor frequency of the MRI system, thereby significantly enhancing the radio frequency magnetic field of the breast region in the cavity of the bilateral circularly polarized intelligent metamaterial radio frequency enhancer. When switching to the unilateral (single breast) imaging mode, the digital capacitance of the circularly polarized intelligent metamaterial radio frequency enhancer on one side that needs to be focused on imaging is adjusted to match the resonant frequency of the circularly polarized intelligent metamaterial radio frequency enhancer 1 on that side with the Larmor frequency of the MRI system, and at the same time, the digital capacitance of the circularly polarized intelligent metamaterial radio frequency enhancer on the other side is adjusted to detune it, so that the radio frequency magnetic field of the breast region in the cavity of only one side of the circularly polarized intelligent metamaterial radio frequency enhancer is more significantly enhanced while the other side is hardly enhanced. This design allows medical personnel to easily select the target area for focused imaging when detecting suspicious lesions, improving detection efficiency and accuracy. This flexible imaging mode switching enhances the applicability of the device and meets different clinical needs.

[0027] Through the above technical features, the circularly polarized intelligent metamaterial radio frequency enhancer of the present invention has the characteristics of circularly polarized radio frequency magnetic field enhancement, dynamic tuning, flexible switching between unilateral and bilateral breast imaging modes, easy availability of materials, simple structure, etc. It will show excellent performance in bilateral breast MRI imaging, provide higher imaging quality and operational convenience, have broad clinical application potential, and can promote its more effective application in the field of MRI.

[0028] The double breast magnetic resonance imaging system proposed in the present invention includes the above-mentioned circularly polarized intelligent metamaterial radio frequency enhancer and has all the characteristics of the above-mentioned circularly polarized intelligent metamaterial radio frequency enhancer, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 A three-dimensional diagram of a circularly polarized smart metamaterial radio frequency enhancer disclosed in an embodiment of the present invention;

[0031] Figure 2 for Figure 1Axial schematic diagram of the medium circular polarization smart metamaterial RF enhancer (top view);

[0032] Figure 3 for Figure 2 A front view of

[0033] Figure 4 for Figure 2 Side view of

[0034] Figure 5 It is a schematic diagram of the structure of the radio frequency coil and the shielding layer in the double breast magnetic resonance imaging system;

[0035] Figure 6 It is a schematic diagram of the structure of the human body model in the radio frequency coil;

[0036] Figure 7 A schematic diagram of a pair of circularly polarized smart metamaterial radio frequency enhancers used in bilateral breast MRI;

[0037] Figure 8 A graph showing the relationship between the RF field intensity and the frequency generated in the RF coil when there is no circularly polarized smart metamaterial RF enhancer;

[0038] Fig. 9 is a graph showing the relationship between the RF field intensity and the frequency generated in the RF coil when there is a circularly polarized smart metamaterial RF enhancer;

[0039] Fig.10 The RF field distribution diagram of the magnetic resonance imaging system when there is no circularly polarized smart metamaterial RF enhancer;

[0040] Fig.11 is a radio frequency field distribution diagram of a magnetic resonance imaging system with a circularly polarized smart metamaterial radio frequency enhancer, and when a pair of circularly polarized smart metamaterial radio frequency enhancers are in a bilateral (double breast) mode;

[0041] Fig.12 is a radio frequency field distribution diagram of a magnetic resonance imaging system with a circularly polarized smart metamaterial radio frequency enhancer, and when a pair of circularly polarized smart metamaterial radio frequency enhancers are in a unilateral (single breast) mode;

[0042] In the figure, the reference numerals are:

[0043] 1. Circularly polarized intelligent metamaterial radio frequency enhancer; 11. Hollow cylindrical dielectric substrate; 12. Conductor ring; 121. Opening; 13. Conductor connector; 14. Adjustable capacitor;

[0044] 2. Double breast magnetic resonance imaging system;

[0045] 3. RF coil; 31. end ring; 32. horizontal bar; 33. excitation port;

[0046] 4. Electromagnetic shielding layer;

[0047] 5. Human body model. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] One of the purposes of the present invention is to provide a circularly polarized intelligent metamaterial radio frequency enhancer for magnetic resonance imaging, which can achieve circularly polarized radio frequency magnetic field enhancement and has the ability to switch between unilateral and bilateral breast imaging modes. The material is easy to obtain, the cost is low, the structure is simple, and the performance of bilateral breast MRI can be greatly improved, thereby solving the problems existing in the above-mentioned existing metamaterial resonators for bilateral breast MRI.

[0050] Another object of the present invention is to provide a double breast magnetic resonance imaging system comprising the above circularly polarized intelligent metamaterial radio frequency enhancer, which can achieve circularly polarized radio frequency magnetic field enhancement and has the ability to switch between unilateral and bilateral breast imaging modes. The material is easy to obtain and the cost is low. The structure is simple and the performance of double breast MRI can be greatly improved, thereby solving the problems existing in the above existing double breast MRI metamaterial resonators.

[0051] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] Example 1

[0053] like Figure 1 to Figure 4As shown, this embodiment provides a circularly polarized smart metamaterial radio frequency enhancer 1, which includes a hollow cylindrical dielectric substrate 11, a conductor ring 12, a conductor connector 13 and an adjustable capacitor 14, wherein: the outer ring of the hollow cylindrical dielectric substrate 11 is provided with a plurality of conductor rings 12 along its axial direction, and any conductor ring 12 is provided with an opening 121 (i.e., the disconnected position of the conductor ring 12) in the circumferential direction of the conductor ring 12, and an adjustable capacitor 14 is provided in the opening 121 of any conductor ring 12; any two adjacent conductor rings 12 are connected by a conductor connector 13. The radio frequency enhancer adopts metamaterial technology to replace traditional ceramics and electromagnetic coils, and has the ability to be seamlessly integrated into the actual medical environment. Its structural design uses a conductor ring 12 with an opening 121, an adjustable capacitor 14 and a conductor connector 13 to form a loop structure that is sensitive to two orthogonal linear polarization magnetic field components at the same time. This design realizes the circular polarization enhancement of the radio frequency magnetic field, which not only improves the signal-to-noise ratio of the region of interest, but also avoids the complexity brought by the combination of traditional linear resonators. In order to meet the basic needs of double breast magnetic resonance imaging, the circularly polarized intelligent metamaterial radio frequency enhancer 1 is generally used in pairs in a breast magnetic resonance system. At the same time, through the intelligent tunable application of the adjustable capacitor 14, the entire circularly polarized intelligent metamaterial radio frequency enhancer 1 allows the capacitance value to be quickly adjusted according to specific imaging requirements, so that the breast magnetic resonance system can maintain the best resonant state under different conditions, further improving the imaging quality and flexibility. In addition, through the design of the adjustable capacitor 14, the circularly polarized intelligent metamaterial radio frequency enhancer 1 also has the flexible unilateral (single breast) and bilateral (double breast) imaging mode switching capabilities, and can select the imaging mode according to actual needs without changing its mechanical structure and relative position. A pair of circularly polarized intelligent metamaterial radio frequency enhancers 1 correspond to the positions of the two breasts of the human body in the breast magnetic resonance system. In the bilateral (double breast) imaging mode, two breasts can be imaged at the same time, and the signal-to-noise ratio is high; in the unilateral (single breast) mode, the signal-to-noise ratio is further improved, which is suitable for detailed inspection of suspicious lesions of the unilateral breast.

[0054] In one embodiment, any two adjacent conductor rings 12 are spaced apart in the axial direction of the hollow cylindrical dielectric substrate 11, and form an axial spacing of the guide rings. In practical applications, the axial spacing of all guide rings can be completely identical, completely different, or not completely identical. Completely different or not completely identical are both forms of non-equidistant arrangement of the conductor rings 12 on the hollow cylindrical dielectric substrate 11. Specifically: when a completely different arrangement is adopted, the axial spacing of the guide rings can be regularly increased or regularly decreased along the axial direction of the hollow cylindrical dielectric substrate 11, such as arithmetic increase or arithmetic decrease. When a not completely identical arrangement is adopted, the axial spacing of some continuous guide rings can be the same, and the axial spacing of the remaining guide rings can be different, or two types of guide ring axial spacing can be adopted, and the two types of guide ring axial spacings are arranged along the axial spacing of the hollow cylindrical dielectric substrate 11. The above-mentioned guide ring axial spacings are arranged in various forms and can be set to different layout modes according to needs.

[0055] In one embodiment, the hollow cylindrical dielectric substrate 11 may be a cylindrical dielectric substrate or a prismatic dielectric substrate, and the prismatic dielectric substrate may be, but is not limited to, a regular quadrangular prism dielectric substrate, a triangular prism dielectric substrate, or a hexagonal prism dielectric substrate, etc. Correspondingly, any conductor ring 12 may be a circular ring, an elliptical ring, or a polygonal ring, and the polygonal ring may be, but is not limited to, a triangle, a quadrilateral, or a pentagon, etc. The hollow cylindrical dielectric substrate 11 and the conductor ring 12 may be randomly combined, for example, when the hollow cylindrical dielectric substrate 11 is a cylindrical dielectric substrate, the conductor ring 12 may be a circular ring, an elliptical ring, or a polygonal ring, or when the hollow cylindrical dielectric substrate 11 is a prismatic dielectric substrate, the conductor ring 12 may also be a circular ring, an elliptical ring, or a polygonal ring. The shapes of all the conductor rings 12 on the hollow cylindrical dielectric substrate 11 may be completely identical, completely different, or not completely identical, and generally adopt a completely identical form, for example, all the conductor rings 12 are circular rings or rectangular rings. Regardless of the combination of the hollow cylindrical dielectric substrate 11 and the conductor ring 12, the hollow cylindrical dielectric substrate 11 and the conductor ring 12 can be fixed by, but not limited to, bonding or friction contact fixation. Taking friction contact fixation as an example, the conductor ring 12 has multiple points that can be interference fit with the outer wall of the hollow cylindrical dielectric substrate 11, so that the friction contact between the two can be used to fix the position of the conductor ring 12 on the hollow cylindrical dielectric substrate 11.

[0056] In a specific embodiment, the hollow cylindrical dielectric substrate 11 may be preferably a cylindrical dielectric substrate, any conductor ring 12 may be a circular ring, and the inner diameter of any conductor ring 12 may be preferably designed to be the same as the outer diameter of the hollow cylindrical dielectric substrate 11, so that any conductor ring 12 is fixed with an interference fit to the outer wall of the hollow cylindrical dielectric substrate 11. At the same time, the conductor rings 12 are preferably arranged equidistantly in the axial direction of the hollow cylindrical dielectric substrate 11 (that is, the axial spacing of all guide rings is exactly the same).

[0057] In one embodiment, any conductor ring 12 may be provided with a plurality of openings 121 spaced apart from each other. Figure 1 to Figure 4 As shown, taking any conductor ring 12 as a circular ring as an example, any conductor ring 12 is provided with two openings 121 at intervals, and the two openings 121 are arranged symmetrically at 180 degrees, and the openings 121 of all conductor rings 12 are axially aligned, so that two rows of openings 121 are symmetrically formed on both sides of all conductor rings 12. Based on this, the conductor connector 13 can be preferably a conductor column, which is parallel to the axial direction of the hollow cylindrical dielectric substrate 11, and the conductor column sequentially passes through all conductor rings 12, so as to achieve the connection between any two adjacent conductor rings 12. Figure 1 to Figure 4 As shown, two conductor posts may be provided in total, and the two conductor posts are arranged symmetrically at 180°, and on the cross section of the cylindrical dielectric substrate, the connection line of the two conductor posts is perpendicular to the connection line of the two columns of openings 121 .

[0058] In one embodiment, the conductor post can be integrally formed with the half ring of each conductor ring 12, such as integrally cut and formed on a copper material. In addition, the conductor post can also be assembled and connected with the half ring of each conductor ring 12. Specifically, each half ring of the conductor ring 12 is provided with a through hole, and the conductor post passes through the through hole and is welded to the conductor ring 12.

[0059] The working principle of the circularly polarized smart metamaterial radio frequency enhancer 1 is as follows: several layers of conductor rings 12 with openings 121 are installed on a hollow cylindrical dielectric substrate 11. The conductor rings 12 stacked and arranged longitudinally (i.e., in the axial direction of the hollow cylindrical dielectric substrate 11) can interact with the magnetic field component polarized along the central axial direction of the conductor ring 12. When the magnetic field component polarized along the central axial direction of the conductor ring 12 is excited by the magnetic field at its resonant frequency, the induced circulating current is distributed along each layer of the conductor ring 12, resulting in a resonance enhancement of the local magnetic field in the center of the conductor ring 12; the symmetrical sides of the portion of the conductor ring 12 without the opening 121 are divided into A conductor column is separately provided to penetrate and connect the conductor ring 12. The two conductor columns and each layer of the conductor ring 12 form a longitudinal loop. Similar to the induction of the conductor ring 12 to the magnetic field, this loop can interact with the magnetic field component perpendicular to the polarization sensitive direction of the conductor ring 12. The transmitting field and receiving field generated by the radio frequency coil 3 in MRI, such as the birdcage coil, are both transverse magnetic fields, which are circularly polarized around the static magnetic field B0. The circularly polarized radio frequency magnetic field can be decomposed into two mutually perpendicular linearly polarized magnetic field components x and y, which can be excited by the circularly polarized smart metamaterial radio frequency enhancer 1.

[0060] The circularly polarized intelligent metamaterial radio frequency enhancer 1 must be used in pairs when used for double breast magnetic resonance imaging.

[0061] In one embodiment, the two electrodes of the adjustable capacitor 14 are electrically connected to the two ends of the corresponding opening 121 . In practical applications, a fixing solution of welding the two electrodes of the adjustable capacitor 14 to the two ends of the corresponding opening 121 can be adopted.

[0062] In one embodiment, the adjustable capacitor 14 is preferably a digital capacitor. A digital capacitor is a digital capacitor. Through the application of intelligent tunable digital capacitors, the capacitance value can be quickly adjusted according to specific imaging requirements, so that the magnetic resonance imaging system can maintain the best resonant state under different conditions, further improving the imaging quality and flexibility. In addition, the setting of the digital capacitor enables the entire radio frequency enhancer to have flexible unilateral (single breast) and bilateral (double breast) imaging mode switching capabilities, and can select the imaging mode according to actual needs without changing the mechanical structure and relative position of the radio frequency enhancer. Specifically, in the bilateral (double breast) imaging mode, the digital capacitance of the bilateral circularly polarized intelligent metamaterial RF enhancer 1 is intelligently adjusted to match the resonant frequency of the bilateral circularly polarized intelligent metamaterial RF enhancer 1 with the Larmor frequency of the MRI system, thereby significantly enhancing the RF magnetic field of the breast area in the cavity of the bilateral circularly polarized intelligent metamaterial RF enhancer 1. When switching to the unilateral (single breast) imaging mode, the digital capacitance of the circularly polarized intelligent metamaterial RF enhancer 1 on one side that needs to be focused on is adjusted to match the resonant frequency of the circularly polarized intelligent metamaterial RF enhancer 1 on that side with the Larmor frequency of the MRI system, and at the same time, the digital capacitance of the circularly polarized intelligent metamaterial RF enhancer 1 on the other side is adjusted to detune it, thereby significantly enhancing the RF magnetic field of the breast area in the cavity of only one side of the circularly polarized intelligent metamaterial RF enhancer 1 while the other side is hardly enhanced. This design allows medical personnel to easily select the target area for concentrated imaging when detecting suspicious lesions, thereby improving detection efficiency and accuracy. This flexible imaging mode switching enhances the applicability of the equipment and meets different clinical needs. .

[0063] The following takes the modeling and simulation of a double breast magnetic resonance imaging system 2 in professional electromagnetic simulation software as an example to verify and illustrate the working principle and technical effect of the circularly polarized intelligent metamaterial radio frequency enhancer 1 in this embodiment.

[0064] In the circularly polarized intelligent metamaterial radio frequency enhancer 1: any conductor ring 12 is a copper ring formed by bending a solid copper tube, the cross-sectional radius of the solid copper tube is 1.9 mm, the inner diameter of the conductor ring 12 is 144.2 mm, the opening 121 is a fan-shaped notch, and the minimum spacing of the notch is 4 mm; the hollow cylindrical dielectric substrate 11 is preferably an insulating material, using but not limited to an acrylic plate, the outer diameter of the hollow cylindrical dielectric substrate 11 is 144.2 mm, and the inner diameter is 138.2 mm. A total of 13 layers of conductor rings 12 are sleeved outside the hollow cylindrical dielectric substrate 11, and the axial spacing between any two adjacent conductor rings 12 is 9 mm. Any conductor ring 12 can be directly interference-fitted with the hollow cylindrical dielectric substrate 11, or can be interference-fitted and then bonded; the above-mentioned conductor column is preferably a solid copper column, the axial length of the solid copper column is 111.8 mm, and the cross-sectional radius is 1.36 mm.

[0065] The circularly polarized smart metamaterial radio frequency enhancers 1 are used in pairs.

[0066] The static magnetic field of the double breast magnetic resonance imaging system 2 is 1.5 T, and the corresponding Larmor frequency of hydrogen protons is 63.8 MHz, which is the resonant frequency of the designed circularly polarized smart metamaterial radio frequency enhancer 1 .

[0067] A birdcage coil is used as the radio frequency coil 3 of the double breast magnetic resonance imaging system 2. Figure 5 As shown, the birdcage coil is composed of two end rings 31 made of conductor and several horizontal bars 32. An electromagnetic shielding layer 4 is arranged on the periphery of the birdcage coil, and two excitation ports 33 with a phase difference of 90° are arranged on the birdcage coil for orthogonal excitation to generate a circularly polarized radio frequency magnetic field. Using a magnetic field probe located at the geometric center of the birdcage coil, it is observed that the double breast magnetic resonance imaging system 2 without the circularly polarized smart metamaterial radio frequency enhancer 1 operates at 63.8MHz, as shown in FIG. Figure 8 As shown, the numerical calculation spectrum of the magnetic field probe shows that the peak values ​​of the x and y components of the magnetic field intensity are both at a frequency of 63.8 MHz, and the peak intensities of the x and y components are both about 0.3 A / m, which indicates that the RF magnetic field excited by the birdcage coil is circularly polarized and the resonant frequency is at 63.8 MHz.

[0068] When a pair of circularly polarized smart metamaterial RF enhancers 1 is placed in the center of the birdcage coil, Figure 7 As shown, the capacitance value of each adjustable capacitor 14 in a pair of circularly polarized smart metamaterial RF enhancers 1 is adjusted to 7.95 pF. A magnetic field probe located at the geometric center of the birdcage coil is used, such as Fig. 9As shown in the figure, the numerical calculation spectrum of the magnetic field probe shows that the peak values ​​of the x and y components of the magnetic field intensity are both at a frequency of 63.8MHz, and the peak intensities of the x and y components are both around 10A / m, so the central magnetic field intensity is significantly enhanced in terms of both the x and y components. This shows that the circularly polarized smart metamaterial RF enhancer 1 can enhance all components of the circularly polarized magnetic field generated by the birdcage coil, fully utilize the RF power, and the resonant frequency of the circularly polarized smart metamaterial RF enhancer 1 and the birdcage coil is matched at 63.8MHz.

[0069] The female human body model 5 is placed in the center of the birdcage coil to form a double breast MRI system without metamaterials, as shown in FIG. Figure 6 Observe the RF field distribution of the longitudinal section at the center of the human breast model when there is no circularly polarized intelligent metamaterial RF enhancer 1 in the birdcage coil, as shown in Fig.10 shown.

[0070] On the basis of the double breast MRI system without circularly polarized intelligent metamaterial RF enhancer 1, a pair of circularly polarized intelligent metamaterial RF enhancers 1 are introduced, and the pair of circularly polarized intelligent metamaterial RF enhancers 1 are adjusted to the position near the bilateral breasts of the human body model 5, and the excitation port 33 of the birdcage coil is used as the excitation source. When the bilateral (double breast) imaging mode is used, the capacitance value of each adjustable capacitor 14 in the pair of circularly polarized intelligent metamaterial RF enhancers 1 is adjusted to 7.48pF; when the unilateral (single breast) imaging mode is used, the capacitance value of each adjustable capacitor 14 in the detuned side circularly polarized intelligent metamaterial RF enhancer 1 is adjusted to 3pF, and the capacitance value of each adjustable capacitor 14 in the normal working side circularly polarized intelligent metamaterial RF enhancer 1 is adjusted to 8pF. Figure 7 As shown, the RF field distribution of the longitudinal section at the center of the human model 5 when the circularly polarized smart metamaterial RF enhancer 1 is used is observed. When the circularly polarized smart metamaterial RF enhancer 1 is used in the double-sided imaging mode and the single-sided imaging mode, the RF field distribution is as follows: Fig.11 , Fig.12 shown.

[0071] Compare Fig.10 and Fig.11 , Fig.12, it can be seen that: when there is no circularly polarized intelligent metamaterial RF enhancer 1, the RF field in the birdcage coil is evenly distributed, and the intensity is higher near the edge of the coil conductor; when there is a circularly polarized intelligent metamaterial RF enhancer 1, no matter the circularly polarized intelligent metamaterial RF enhancer 1 is in bilateral imaging mode or unilateral imaging mode, the RF field intensity in the cavity of the circularly polarized intelligent metamaterial RF enhancer 1 is significantly improved, while the RF field intensity outside the structure of the circularly polarized intelligent metamaterial RF enhancer 1 is weak; one side of the breast model is selected as the imaging area, and when the circularly polarized intelligent metamaterial RF enhancer 1 is in unilateral (single breast) imaging mode, the RF field intensity in the unilateral breast area is higher than that in the bilateral (double breast) imaging mode. Fig.10 and Fig.11 , Fig.12 The area of ​​the breast model within the middle white dotted line is the target area for RF field enhancement. It is calculated that in the target area, the RF field intensity in the bilateral (double breast) imaging mode using the circularly polarized smart metamaterial RF enhancer 1 is 10.6 times that when the circularly polarized smart metamaterial RF enhancer 1 is not used, and the RF field intensity in the unilateral imaging mode using the circularly polarized smart metamaterial RF enhancer 1 is 16.9 times that of the unilateral breast area when the circularly polarized smart metamaterial RF enhancer 1 is not used.

[0072] It can be seen that the circularly polarized smart metamaterial RF enhancer 1 proposed in this scheme realizes the enhancement of the circular polarization of the integrated RF magnetic field. It realizes the circular polarization enhancement of the RF magnetic field through a single circularly polarized smart metamaterial RF enhancer 1 instead of two separate linearly polarized metamaterial RF enhancers, overcoming the poor effect of the original metamaterial only having linear RF magnetic field enhancement and the cumbersomeness of the multi-coil combination. The conductor ring with an opening and the adjustable capacitor are mainly used to enhance the linear polarization of the axial RF magnetic field of the RF coil, while the linear polarization enhancement of the transverse RF magnetic field of the RF coil is achieved by the conductor column connected to the conductor ring. In addition to having an excellent magnetic field enhancement effect, this simple and unified structure also has the advantages of low manufacturing cost and easy installation. The design of the circularly polarized smart metamaterial RF enhancer 1 effectively enhances the intensity and concentration of the RF magnetic field, thereby significantly improving the imaging signal-to-noise ratio.

[0073] This solution uses digital capacitors that are intelligently tunable, and can adjust the capacitance value of each capacitor through digital signals to change the resonant frequency of the circularly polarized intelligent metamaterial radio frequency enhancer 1, so that the circularly polarized intelligent metamaterial radio frequency enhancer 1 is kept in the best resonant mode during use, that is, the resonant frequency is consistent with the Larmor frequency, thereby achieving the highest imaging signal-to-noise ratio gain, and the image quality is best improved, which is beneficial to actual medical diagnosis. When in use, each digital capacitor is connected to the controller for communication, and the circularly polarized intelligent metamaterial radio frequency enhancer 1 has the function of instant dynamic tuning during the actual magnetic resonance imaging process, so that the circularly polarized intelligent metamaterial radio frequency enhancer 1 is always kept in the best resonant mode, thereby achieving the highest imaging signal-to-noise ratio gain.

[0074] In addition, the present solution adopts the digital capacitor intelligent tunable technology, so that the circularly polarized intelligent metamaterial radio frequency enhancer 1 used in pairs has the ability to flexibly and intelligently switch between unilateral (single breast) and bilateral (bilateral breast) imaging modes. Specifically, in the bilateral (bilateral breast) imaging mode, the digital capacitor of the bilateral circularly polarized intelligent metamaterial radio frequency enhancer 1 is intelligently adjusted to match the resonant frequency of the bilateral circularly polarized intelligent metamaterial radio frequency enhancer 1 with the Larmor frequency of the MRI system, so that the radio frequency magnetic field of the breast area in the cavity of the bilateral circularly polarized intelligent metamaterial radio frequency enhancer 1 is significantly enhanced. When switching to the unilateral (single breast) imaging mode, the digital capacitor of the circularly polarized intelligent metamaterial radio frequency enhancer 1 on one side that needs to be focused on is adjusted to match the resonant frequency of the circularly polarized intelligent metamaterial radio frequency enhancer 1 on that side with the Larmor frequency of the MRI system, and the digital capacitor of the circularly polarized intelligent metamaterial radio frequency enhancer 1 on the other side is adjusted to detune it, so that the radio frequency magnetic field of the breast area in the cavity of only one side of the circularly polarized intelligent metamaterial radio frequency enhancer 1 is more significantly enhanced while the other side is almost not enhanced. This design allows medical personnel to easily select the target area for focused imaging when detecting suspicious lesions, improving detection efficiency and accuracy. This flexible imaging mode switching enhances the applicability of the device and meets different clinical needs.

[0075] Through the above technical features, the circularly polarized intelligent metamaterial radio frequency enhancer 1 of this scheme will show excellent performance in double breast MRI imaging, provide higher imaging quality and operational convenience, and has a wide range of clinical application potential

[0076] It should be noted that the aforementioned RF coil 3 can also be changed to other RF coils that can generate circularly polarized RF magnetic fields in addition to the birdcage coil. The human body model 5 used can be changed to any voxel model; the conductor ring and the conductor column can be changed to other conductors in addition to annealed copper; the material of the dielectric substrate can be changed to other dielectrics in addition to acrylic plates; the openings on each layer of the conductor ring can be at any position, and accordingly, the conductor column and the adjustable capacitor can have any relative position on the basis of maintaining a basic connection relationship with the conductor ring; the use site of the entire circularly polarized intelligent metamaterial RF enhancer 1 can be changed to other human body parts in addition to the breast. After changing to other positions, the circularly polarized intelligent metamaterial RF enhancer 1 also has the effect of enhancing the RF field, and the enhancement amplitude of the RF field can achieve an effect similar to or better than the above-mentioned scheme.

[0077] Example 2

[0078] like Figure 5 to Figure 7 As shown, in this embodiment, a double breast magnetic resonance imaging system 2 is proposed, comprising a radio frequency coil 3 and an electromagnetic shielding layer 4 arranged outside the radio frequency coil 3, wherein the radio frequency coil 3 is used to generate a circularly polarized radio frequency magnetic field. Figure 5 and Figure 7 As shown, the double breast MRI system 2 also includes a pair of circularly polarized intelligent metamaterial radio frequency enhancers 1 as disclosed in Example 1. The pair of circularly polarized intelligent metamaterial radio frequency enhancers 1 are arranged at intervals along the radial direction of the radio frequency coil 3 at the exact center of the radio frequency coil 3. The pair of circularly polarized intelligent metamaterial radio frequency enhancers 1 correspond to the positions of the double breasts of the human body. The axial direction of any circularly polarized intelligent metamaterial radio frequency enhancer 1 is perpendicular to the axial direction of the radio frequency coil 3. Figure 7 shown.

[0079] The use principle and use effect of the above-mentioned double breast magnetic resonance imaging system 2 can all be referred to in Example 1, and the details will not be repeated here.

[0080] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A circularly polarized intelligent metamaterial radio frequency enhancer, characterized in that: It comprises a hollow cylindrical dielectric substrate (11), a conductor ring (12), a conductor connecting piece (13) and an adjustable capacitor (14), wherein: The outer ring of the hollow cylindrical dielectric substrate (11) is sleeved with a plurality of conductor rings (12) along its axial direction; Any one of the conductor rings (12) is provided with an opening (121) in the circumferential direction of the conductor ring (12), and the adjustable capacitor (14) is arranged in the opening (121) of any one of the conductor rings (12); Any two adjacent conductor rings (12) are electrically connected via the conductor connector (13).

2. The circularly polarized smart metamaterial radio frequency enhancer according to claim 1, characterized in that: Any two adjacent conductor rings (12) are spaced apart in the axial direction of the hollow cylindrical dielectric substrate (11) to form an axial spacing of the guide rings.

3. The circularly polarized smart metamaterial radio frequency enhancer according to claim 2, characterized in that: The axial spacings of all the guide rings are completely identical, completely identical or not completely identical.

4. The circularly polarized smart metamaterial radio frequency enhancer according to any one of claims 1 to 3, characterized in that: The hollow columnar dielectric substrate (11) is a cylindrical dielectric substrate or a prismatic dielectric substrate; any one of the conductor rings (12) is a circular ring, an elliptical ring or a polygonal ring.

5. The circularly polarized smart metamaterial radio frequency enhancer according to claim 4, characterized in that: The hollow cylindrical dielectric substrate (11) is a cylindrical dielectric substrate, any one of the conductor rings (12) is a circular ring, and any one of the conductor rings (12) is fixedly sleeved on the outside of the hollow cylindrical dielectric substrate (11).

6. The circularly polarized smart metamaterial radio frequency enhancer according to claim 5, characterized in that: Two openings (121) are arranged at intervals on any one of the conductor rings (12), and the two openings (121) are arranged symmetrically at 180 degrees, and the openings (121) of all the conductor rings (12) are axially aligned.

7. The circularly polarized smart metamaterial radio frequency enhancer according to claim 6, characterized in that: The conductor connecting piece (13) is a conductor column, which is parallel to the axial direction of the hollow cylindrical dielectric substrate (11), and passes through all the conductor rings (12) in sequence to achieve connection between any two adjacent conductor rings (12).

8. The circularly polarized smart metamaterial radio frequency enhancer according to claim 7, characterized in that: Two conductor posts are provided, and the two conductor posts are arranged symmetrically at 180 degrees, and on the cross section of the cylindrical dielectric substrate, the connection line of the two conductor posts is perpendicular to the connection line of the two columns of openings (121).

9. The circularly polarized smart metamaterial radio frequency enhancer according to any one of claims 1 to 3, characterized in that: The adjustable capacitor (14) is a digital capacitor.

10. A double breast magnetic resonance imaging system, comprising a radio frequency coil (3) and an electromagnetic shielding layer (4) arranged outside the radio frequency coil (3), characterized in that: It also includes a pair of circularly polarized smart metamaterial radio frequency enhancers (1) as described in any one of claims 1 to 9, wherein the pair of circularly polarized smart metamaterial radio frequency enhancers (1) are arranged at intervals along the radial direction of the radio frequency coil (3) at the exact center of the radio frequency coil (3), and the axial direction of any one of the circularly polarized smart metamaterial radio frequency enhancers (1) is perpendicular to the axial direction of the radio frequency coil (3).

Images