CN114910843B

CN114910843B - Magnetic field enhancement device

Info

Publication number: CN114910843B
Application number: CN202110183923.5A
Authority: CN
Inventors: 赵乾; 池中海; 郑卓肇; 孟永钢; 周济
Original assignee: Tsinghua University; Beijing Tsinghua Changgeng Hospital
Current assignee: Tsinghua University; Beijing Tsinghua Changgeng Hospital
Priority date: 2021-02-10
Filing date: 2021-02-10
Publication date: 2025-06-03
Anticipated expiration: 2041-02-10
Also published as: CN114910843A; WO2022170751A1

Abstract

The present application relates to a magnetic field enhancement device. A first electrode layer is arranged on a first surface. A second electrode layer is arranged on the first surface and is located in a first capacitance zone, and the second electrode layer is spaced apart from a portion of the first electrode layer located in the first capacitance zone. A third electrode layer is arranged on the first surface and is located in the second capacitance zone, and the third electrode layer is spaced apart from a portion of the first electrode layer located in the second capacitance zone. One end of a first resonant capacitor is electrically connected to the second electrode layer, the other end of the first resonant capacitor is electrically connected to a portion of the first electrode layer located in the first capacitance zone, and the second electrode layers of two adjacent magnetic field enhancement components are connected to portions of the first electrode layer located in the first capacitance zone. One end of a second resonant capacitor is electrically connected to the third electrode layer, the other end of the second resonant capacitor is electrically connected to a portion of the first electrode layer located in the second capacitance zone, and the third electrode layer of two adjacent magnetic field enhancement components is connected to portions of the first electrode layer located in the second capacitance zone.

Description

Magnetic field enhancement device

Technical Field

The application relates to the technical field of magnetic resonance imaging, in particular to a magnetic field enhancement device.

Background

MRI (Magnetic Resonance Imaging ) is a non-invasive detection method, and is an important basic diagnosis technology in the fields of medicine, biology and neuroscience. The signal intensity transmitted by the traditional MRI device mainly depends on the intensity of the static magnetic field B0, and the signal-to-noise ratio and resolution of images can be improved and the scanning time can be shortened by adopting a high magnetic field system and even an ultra-high magnetic field system. However, the increase of static magnetic field strength causes three problems, namely 1) the non-uniformity of a Radio Frequency (RF) field is increased, tuning difficulty is increased, 2) heat generation of human tissues is increased, potential safety hazards are brought, adverse reactions such as dizziness and vomiting are easy to occur to patients, and 3) purchase cost is greatly increased, which is a burden for most small-scale hospitals. Therefore, how to use a static magnetic field strength as small as possible while achieving high imaging quality becomes a critical issue in MRI technology.

The advent of super-structured materials provides a novel and more efficient method for improving MRI imaging quality and efficiency. Super-structured materials have many special properties that natural materials do not possess. The control of the electromagnetic wave propagation path and the electromagnetic field intensity distribution can be realized through the interaction between electromagnetic waves and metal or dielectric elements of the super-structural material and the coupling effect between the elements. The specific working principle is that electromagnetic resonance in a structure formed by the super-structure material is utilized to realize the adjustment of electromagnetic parameters such as anisotropy, gradient distribution and the like. In addition, resonance enhancement of different frequency points can be realized through the design of parameters such as geometric dimension, shape, dielectric constant and the like of the super-structure material.

A conventional magnetic field enhancement assembly includes a dielectric plate and first and second electrodes on the front and back sides of the dielectric plate, respectively. The orthographic projection of the second electrode on the dielectric plate is positioned at both ends of the orthographic projection of the first electrode on the dielectric plate to constitute a parallel plate capacitor.

Parallel plate capacitors formed in the structure of the traditional magnetic field enhancement assemblies are all positioned on a transmission line formed by strip-shaped electrodes, so that the structure formed by connecting a plurality of traditional magnetic field enhancement assemblies is equivalent to a parallel relationship of a plurality of parallel plate capacitors after a circuit. The equivalent capacitance of a structure formed by connecting a plurality of traditional magnetic field enhancement components is close to the sum of the capacitance of a plurality of parallel plate capacitors. Since capacitance is inversely proportional to frequency, at high-field or ultra-high-field MRI systems (3T and above), the frequency increases and the equivalent capacitance of the structure formed by the connection of multiple conventional magnetic field enhancing components becomes smaller. The equivalent capacitance becomes smaller, and the capacitance required for a plurality of parallel plate capacitors becomes correspondingly smaller. The equivalent capacitance of the structure formed by the connection of the plurality of conventional magnetic field enhancement components is close to the sum of the capacitances of the plurality of parallel plate capacitors, so that the capacitances of the plurality of parallel plate capacitors need a small capacitance value.

Therefore, the capacitance value of the plurality of parallel plate capacitors is too small, so that the resonance frequency of the structure formed by connecting the plurality of conventional magnetic field enhancing components fluctuates greatly, resulting in deterioration of the stability of the resonance frequency.

Disclosure of Invention

In view of the above, it is necessary to provide a magnetic field enhancing device.

The application provides a magnetic field enhancement device. The magnetic field enhancement device includes a plurality of magnetic field enhancement components. Each of the magnetic field enhancement assemblies includes a first dielectric layer, a first electrode layer, a second electrode layer, and a third electrode layer. The first dielectric layer has a first end and a second end disposed opposite to each other. The first dielectric layer also has a first surface extending from the first end to the second end.

The first surface includes a first capacitive region, a conductive region, and a second capacitive region from the first end to the second end. The conductive region is located between the first capacitive region and the second capacitive region. The first capacitive region is proximate the first end. The second capacitive region is proximate the second end.

The first electrode layer is arranged on the first surface. The first electrode layer extends from the first end to the second end. The two ends of the first electrode layer extend to the first capacitance region and the second capacitance region respectively. The second electrode layer is arranged on the first surface. The second electrode layer is positioned in the first capacitance region. The second electrode layer and the part of the first electrode layer, which is positioned in the first capacitance area, are arranged at intervals.

The third electrode layer is arranged on the first surface. The third electrode layer is located in the second capacitance region. The third electrode layer and the part of the first electrode layer, which is positioned in the second capacitance area, are arranged at intervals.

Each of the magnetic field enhancement assemblies extends from the first end to the second end. The magnetic field enhancement components are arranged at intervals and surround to form a magnetic field enhancement space. The magnetic field enhancement space is used for placing a tested part and enhancing the magnetic field of the tested part.

The magnetic field enhancement device further includes a plurality of first resonant capacitors. The plurality of first resonant capacitors are disposed proximate the first end. One of the first resonant capacitors is disposed corresponding to one of the magnetic field enhancing components. One end of each first resonant capacitor is electrically connected with the second electrode layer. The other end of each first resonant capacitor is electrically connected with the part of the first electrode layer, which is positioned in the first capacitor region. The second electrode layers of two adjacent magnetic field enhancement assemblies are connected with the parts of the first electrode layers, which are positioned in the first capacitance areas. That is, in two adjacent magnetic field enhancement assemblies, the second electrode layer of one magnetic field enhancement assembly is connected to the portion of the first electrode layer of the other magnetic field enhancement assembly located in the first capacitance region. On the first end side, the plurality of magnetic field enhancement components are connected through the second electrode layer and the part of the first electrode layer, which is positioned in the first capacitance region, in each magnetic field enhancement component.

When the magnetic field enhancing device is arranged in a magnetic field environment, induced current is generated. On the first end side, the induced current sequentially passes through the second electrode layer, two ends of the first resonant capacitor, a portion of the first electrode layer located in the first capacitor region, the second electrode layer adjacent to the magnetic field enhancing component, two ends of the first resonant capacitor, a portion of the first electrode layer located in the first capacitor region, and the like. When equivalent to a circuit diagram, the plurality of first resonance capacitors are sequentially connected in series one by one.

The magnetic field enhancement device further includes a plurality of second resonant capacitors. The plurality of second resonant capacitors are disposed proximate the second end. One of the second resonant capacitors is disposed corresponding to one of the magnetic field enhancing components. One end of each second resonance capacitor is electrically connected with the third electrode layer, and the other end of each second resonance capacitor is electrically connected with a part of the first electrode layer, which is positioned in the second capacitance region. The third electrode layers of two adjacent magnetic field enhancement assemblies are connected with the parts of the first electrode layers, which are positioned in the second capacitance areas. That is, in two adjacent magnetic field enhancement assemblies, the third electrode layer of one magnetic field enhancement assembly is connected to a portion of the first electrode layer of the other magnetic field enhancement assembly located in the second capacitance region. On the second end side, the plurality of magnetic field enhancement components are connected through the third electrode layer and the part of the first electrode layer, which is positioned in the second capacitance region, in each magnetic field enhancement component.

When the magnetic field enhancing device is arranged in a magnetic field environment, induced current is generated. And on one side of the second end, induced current sequentially passes through the third electrode layer, two ends of the second resonance capacitor, a part of the first electrode layer located in the second capacitance region, the third electrode layer adjacent to the magnetic field enhancement component, two ends of the second resonance capacitor, a part of the first electrode layer located in the second capacitance region, and the like. When equivalent to a circuit diagram, the plurality of second resonance capacitors are sequentially connected in series one by one.

The first electrode layer, the second electrode layer and the third electrode layer are all arranged on the first surface. The first electrode layer, the second electrode layer, and the third electrode layer are disposed on the same surface without forming a parallel plate capacitor therebetween. The first electrode layer, the second electrode layer and the third electrode layer are all arranged at intervals and are not connected with each other. In the first capacitance region, the second electrode layer and the first electrode layer are arranged on the same surface in a spaced mode. And two ends of the first resonance capacitor are respectively and electrically connected with the second electrode layer and the first electrode layer. In the second capacitance region, two ends of the second resonance capacitor are respectively and electrically connected with the third electrode layer and the first electrode layer.

When the magnetic field enhancement components are connected and placed in a magnetic field environment, the first resonant capacitors are sequentially connected in series one by one. The plurality of second resonance capacitors are sequentially connected in series one by one. The magnetic field enhancement means may enhance the magnetic field when the operating frequency of the high-field or ultra-high-field MRI system (3T and above) is the same as the resonance frequency of the magnetic field enhancement means.

Since capacitance is inversely proportional to frequency, in high-field or ultra-high-field MRI systems (3T and above), the frequency is relatively large and the equivalent capacitance of the structure formed by the connection of multiple conventional magnetic field enhancing components needs to be relatively small. However, the plurality of first resonance capacitances are connected in series such that an equivalent capacitance formed by the plurality of first resonance capacitances becomes smaller. The plurality of second resonance capacitors are connected in series so that the equivalent capacitance formed by the plurality of second resonance capacitors becomes smaller. When the capacitance values in the resonance frequency of the magnetic field enhancement device are assigned to the plurality of first resonance capacitances and the plurality of second resonance capacitances, the capacitance values of the plurality of first resonance capacitances and the plurality of second resonance capacitances can take a large capacitance value, avoiding taking a capacitor with an excessively small capacitance value. The capacitor with a large capacitance value is adopted, so that the resonance frequency fluctuation of a structure formed by the magnetic field enhancement device is small, the stability of the resonance frequency is improved, and the magnetic field enhancement device is more suitable for high-field MRI.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments or the conventional techniques of the present application, the drawings required for the descriptions of the embodiments or the conventional techniques will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to the drawings without inventive effort for those skilled in the art.

FIG. 1 is a schematic diagram of an exploded view of a magnetic field enhancement assembly according to one embodiment of the present application;

FIG. 2 is a schematic diagram of a magnetic field enhancement device according to an embodiment of the present application;

FIG. 3 is a top view of a magnetic field enhancement assembly according to one embodiment of the present application;

FIG. 4 is an equivalent circuit diagram of a magnetic field enhancement device according to an embodiment of the present application;

FIG. 5 is a top view of a magnetic field enhancement assembly according to one embodiment of the present application;

FIG. 6 is a schematic diagram of a magnetic field enhancement device according to an embodiment of the present application;

FIG. 7 is a top view of a magnetic field enhancement assembly according to one embodiment of the present application;

FIG. 8 is a top view of a magnetic field enhancement assembly according to one embodiment of the present application;

FIG. 9 is a top view of a magnetic field enhancement assembly according to one embodiment of the present application;

FIG. 10 is a schematic diagram of a magnetic field enhancement device according to an embodiment of the present application;

FIG. 11 is a schematic diagram of a magnetic field enhancement device according to an embodiment of the present application;

FIG. 12 is a schematic diagram showing the connection structure of the magnetic field enhancement assembly, the third conductive structure, the fourth conductive structure, the first resonant capacitor and the second resonant capacitor shown in FIG. 11 according to the present application;

FIG. 13 is a top view of a magnetic field enhancement assembly according to one embodiment of the present application;

FIG. 14 is a side view of a magnetic field enhancement assembly in one embodiment provided by the present application;

FIG. 15 is a side view of a first end of a magnetic field enhancement assembly in accordance with one embodiment of the present application;

FIG. 16 is a side view of a second end of a magnetic field enhancement assembly in accordance with one embodiment of the present application;

FIG. 17 is a side view of a magnetic field enhancement assembly in accordance with one embodiment of the present application;

FIG. 18 is a schematic diagram of a magnetic field enhancement device according to an embodiment of the present application;

FIG. 19 is a schematic view of a magnetic field enhancement device according to an embodiment of the present application;

FIG. 20 is a graph showing the resonant frequency of a magnetic field enhancement device according to an embodiment of the present application;

Fig. 21 shows a magnetic field distribution of the magnetic field enhancement device according to an embodiment of the present application.

Reference numerals illustrate:

The magnetic field enhancement device 20, the magnetic field enhancement component 10, the first dielectric layer 100, the first electrode layer 110, the second electrode layer 120, the third electrode layer 130, the first end 103, the second end 104, the first surface 101, the second surface 102, the first capacitance region 11, the conductive region 13, the second capacitance region 12, the magnetic field enhancement space 105, the first resonance capacitance 911, the second resonance capacitance 921, the first conductive structure 519, the second conductive structure 529, the fifth diode 461, the sixth diode 462, the fifth external capacitance 445, the first depletion MOS tube 231, the second depletion MOS tube 232, the third conductive structure 539, the fourth conductive structure 549, the first inductance 241, the third diode 213, the fourth diode 214, the cylindrical support structure 50, the third end 51, the fourth end 53, the inner surface 521, the outer surface 522, the detection space 509, the fourth electrode layer 140, the first structural capacitance 151, the second structural capacitance 152, the first external capacitance 440, the first diode 431, the second diode 432.

Detailed Description

In order that the application may be readily understood, a more complete description of the application will be rendered by reference to the appended drawings. Embodiments of the application are illustrated in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

It will be understood that the terms first, second, etc. as used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another element. For example, a first resistance may be referred to as a second resistance, and similarly, a second resistance may be referred to as a first resistance, without departing from the scope of the application. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

It is to be understood that in the following embodiments, "connected" is understood to mean "electrically connected", "communicatively connected", etc., if the connected circuits, modules, units, etc., have electrical or data transfer between them.

As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," and/or the like, specify the presence of stated features, integers, steps, operations, elements, components, or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof. Also, the term "and/or" as used in this specification includes any and all combinations of the associated listed items.

Referring to fig. 1, the present application provides a magnetic field enhancing device 20. The magnetic field enhancement device 20 includes a plurality of magnetic field enhancement assemblies 10. Each of the magnetic field enhancement assemblies 10 includes a first dielectric layer 100, a first electrode layer 110, a second electrode layer 120, and a third electrode layer 130. The first dielectric layer 100 has a first end 103 and a second end 104 disposed opposite each other. The first dielectric layer 100 also has a first surface 101 extending from the first end 103 to the second end 104.

The first surface 101 comprises a first capacitive area 11, a conductive area 13 and a second capacitive area 12 in a direction from the first end 103 to the second end 104. The conductive region 13 is located between the first capacitive region 11 and the second capacitive region 12. The first capacitive area 11 is near the first end 103. The second capacitive area 12 is near the second end 104.

The first electrode layer 110 is disposed on the first surface 101. The first electrode layer 110 extends from the first end 103 to the second end 104. Both ends of the first electrode layer 110 extend toward the first capacitance region 11 and the second capacitance region 12, respectively. The second electrode layer 120 is disposed on the first surface 101. The second electrode layer 120 is located in the first capacitance region 11. The second electrode layer 120 is spaced from a portion of the first electrode layer 110 located in the first capacitance region 11.

The third electrode layer 130 is disposed on the first surface 101. The third electrode layer 130 is located in the second capacitance region 12. The third electrode layer 130 is spaced apart from a portion of the first electrode layer 110 located in the second capacitance region 12.

Referring to fig. 2, each of the magnetic field enhancement assemblies 10 extends from the first end 103 to the second end 104. The plurality of magnetic field enhancement assemblies 10 are spaced apart and surround to form a magnetic field enhancement space 105. The magnetic field enhancement space 105 is used for placing a tested part, and further enhancing the magnetic field of the tested part.

Referring to fig. 3, the magnetic field enhancement device 20 further includes a plurality of first resonant capacitors 911. The plurality of first resonant capacitors 911 are disposed proximate the first end 103. One of the first resonant capacitors 911 is provided corresponding to one of the magnetic field enhancing members 10. One end of each of the first resonant capacitors 911 is electrically connected to the second electrode layer 120. The other end of each of the first resonance capacitors 911 is electrically connected to a portion of the first electrode layer 110 located in the first capacitance region 11. The second electrode layers 120 of two adjacent magnetic field enhancement assemblies 10 are connected to the portions of the first electrode layers 110 located in the first capacitance region 11. That is, in two adjacent magnetic field enhancement assemblies 10, the second electrode layer 120 of one magnetic field enhancement assembly 10 is connected to the portion of the first electrode layer 110 of the other magnetic field enhancement assembly 10 located in the first capacitance region 11. On the side of the first end 103, the plurality of magnetic field enhancement assemblies 10 are connected by the second electrode layer 120 and the portion of the first electrode layer 110 in each of the magnetic field enhancement assemblies 10 located in the first capacitance region 11.

When the magnetic field enhancement device 20 is placed in a magnetic field environment, an induced current is generated. On the first end 103 side, the induced current sequentially passes through the second electrode layer 120, two ends of the first resonant capacitor 911, a portion of the first electrode layer 110 located in the first capacitor region 11, the second electrode layer 120 adjacent to the magnetic field enhancing component 10, two ends of the first resonant capacitor 911, a portion of the first electrode layer 110 located in the first capacitor region 11, and so on. Referring to fig. 4, when equivalent to a circuit diagram, the plurality of first resonant capacitors 911 are sequentially connected in series one by one.

The magnetic field enhancement means 20 further comprises a plurality of second resonance capacitors 921. The plurality of second resonant capacitors 921 is disposed proximate the second end 104. One of the second resonance capacitances 921 is disposed corresponding to one of the magnetic field enhancement assemblies 10. One end of each second resonance capacitor 921 is electrically connected to the third electrode layer 130, and the other end of each second resonance capacitor 921 is electrically connected to a portion of the first electrode layer 110 located in the second capacitance region 12. The third electrode layers 130 of two adjacent magnetic field enhancement assemblies 10 are connected to the portions of the first electrode layer 110 located in the second capacitance region 12. That is, in two adjacent magnetic field enhancement assemblies 10, the third electrode layer 130 of one magnetic field enhancement assembly 10 is connected to the portion of the first electrode layer 110 of the other magnetic field enhancement assembly 10 located in the second capacitance region 12. On the side of the second end 104, the plurality of magnetic field enhancement assemblies 10 are connected by the third electrode layer 130 and the portion of the first electrode layer 110 in each of the magnetic field enhancement assemblies 10 located in the second capacitance region 12.

When the magnetic field enhancement device 20 is placed in a magnetic field environment, an induced current is generated. On the second end 104 side, the induced current sequentially passes through the third electrode layer 130, two ends of the second resonant capacitor 921, a portion of the first electrode layer 110 located in the second capacitor region 12, the third electrode layer 130 adjacent to the magnetic field enhancing component 10, two ends of the second resonant capacitor 921, a portion of the first electrode layer 110 located in the second capacitor region 12, and so on. Referring to fig. 4, when equivalent to a circuit diagram, the plurality of second resonance capacitors 921 are sequentially connected in series one by one.

The first electrode layer 110, the second electrode layer 120, and the third electrode layer 130 are all disposed on the first surface 101. The first electrode layer 110, the second electrode layer 120, and the third electrode layer 130 are disposed on the same surface, and no parallel plate capacitor is formed therebetween. The first electrode layer 110, the second electrode layer 120, and the third electrode layer 130 are all disposed at intervals, and are not connected to each other. In the first capacitance region 11, the second electrode layer 120 and the first electrode layer 110 are disposed on the same surface at intervals. Both ends of the first resonant capacitor 911 are electrically connected to the second electrode layer 120 and the first electrode layer 110, respectively. In the second capacitance region 12, both ends of the second resonance capacitance 921 are electrically connected to the third electrode layer 130 and the first electrode layer 110, respectively.

When the plurality of magnetic field enhancement members 10 are connected and placed in a magnetic field environment, the plurality of first resonance capacitors 911 are sequentially connected in series one by one. The plurality of second resonance capacitors 921 are sequentially connected in series one by one. The magnetic field enhancement means 20 may enhance the magnetic field when the operating frequency of the high-field or ultra-high-field MRI system (3T and above) is the same as the resonance frequency of the magnetic field enhancement means 20.

Since capacitance is inversely proportional to frequency, in high-field or ultra-high-field MRI systems (3T and above), the frequency is relatively large, which may make the equivalent capacitance of a structure formed by connecting multiple conventional magnetic field enhancing components relatively small. However, the plurality of first resonance capacitors 911 are connected in series such that the equivalent capacitance formed by the plurality of first resonance capacitors 911 becomes smaller. The plurality of second resonance capacitors 921 are connected in series such that an equivalent capacitance formed by the plurality of second resonance capacitors 921 becomes smaller. When the capacitance values in the resonance frequency of the magnetic field enhancement device 20 are assigned to the plurality of first resonance capacitances 911 and the plurality of second resonance capacitances 921, the capacitance values of the plurality of first resonance capacitances 911 and the plurality of second resonance capacitances 921 can take on large capacitance values, avoiding the use of capacitors with excessively small capacitance values. The capacitor with large capacitance value makes the resonance frequency fluctuation of the magnetic field enhancement device 20 smaller, improves the stability of the resonance frequency, and is more suitable for high-field MRI.

The magnetic field enhancement device 20 is a high frequency MRI image enhanced super-structured surface device. The high-frequency MRI image enhanced super-structure surface device enables the super-structure surface to have a larger capacitance value under high-frequency operation, and avoids capacitance with an excessively small capacitance value. The high-frequency MRI image enhancement super-structure surface device avoids the adoption of a capacitance with an excessively small capacitance value, and increases the adjustability and resonance frequency stability of the high-frequency MRI image enhancement super-structure surface device under the high-frequency working condition.

The high-frequency MRI image enhancement super-structure surface device adopts a capacitor with a large capacitance value to enable the resonance frequency fluctuation of the high-frequency MRI image enhancement super-structure surface device to be smaller. The high-frequency MRI image enhancement super-structure surface device adopts a capacitor with a large capacitance value, improves the stability of the resonance frequency of the high-frequency MRI image enhancement super-structure surface device, and is more suitable for high-field MRI.

In one embodiment, the materials of the first electrode layer 110, the second electrode layer 120, and the third electrode layer 130 may be nonmagnetic metals such as copper, silver, gold, and the like. The material of the first dielectric layer 100 may be a material having a flame-retardant material grade of FR4, a high-temperature resistant thermoplastic resin such as polyphenylene oxide (PPE), or Rogers 4003C material.

In one embodiment, the materials of the first electrode layer 110, the second electrode layer 120, and the third electrode layer 130 are the same and are copper foils.

Referring to fig. 5, in one embodiment, in the first capacitance region 11, the first resonant capacitor 911 is disposed on the first surface 101. In the second capacitance region 12, the second resonance capacitance 921 is disposed on the first surface 101.

In the first capacitance region 11, the second electrode layer 120 is disposed at a distance from the first electrode layer 110. The opposite end of the second electrode layer 120 and the first electrode layer 110 form a first gap, and the first surface 101 is exposed. The first resonant capacitor 911 is disposed on the first surface 101 in the first gap. In the second capacitance region 12, the third electrode 130 is disposed at a distance from the first electrode layer 110. The third electrode 130 and the opposite port of the first electrode layer 110 form a second gap, and expose the first surface 101. The second resonance capacitor 921 is disposed on the first surface 101 in the second gap.

The first resonant capacitor 911 is disposed on the first surface 101 in the first gap, and two ends of the first resonant capacitor 911 may be electrically connected to the second electrode layer 120 and the first electrode layer 110 with fewer wires. The second resonant capacitor 921 is disposed on the first surface 101 in the second gap, and two ends of the second resonant capacitor 921 may be electrically connected to the third electrode 130 and the first electrode layer 110 with fewer wires. Since the number of the leads connected with the capacitor is small, excessive inductance introduced by the leads can be avoided, and the resonance frequency of the magnetic field enhancement device 20 is influenced, so that the resonance frequency fluctuation of the magnetic field enhancement device 20 is small, the stability of the resonance frequency is improved, and the magnetic field enhancement device is more suitable for high-field MRI.

In one embodiment, the magnetic field formed by the first electrode layer 110 located in the conductive region 13 is the primary magnetic field of the magnetic field enhancing means 20. The space surrounded by the first electrode layer 110 located in the conductive region 13 is a main magnetic field enhancement space. The first resonance capacitance 911 and the second resonance capacitance 921 are symmetrical with respect to the first electrode layer 110 in the conductive region 13. The first resonant capacitor 911 and the second resonant capacitor 921 are symmetrically disposed at the first end 103 and the second end 104, respectively, so that the magnetic field formed by the magnetic field enhancing device 20 is more uniform and symmetrical, which is more beneficial to detecting the detection part and improving the image quality of the MRI apparatus. The first resonant capacitor 911 and the second resonant capacitor 921 are symmetrically disposed at the first end 103 and the second end 104, so that the first resonant capacitor 911 and the second resonant capacitor 921 are far away from the magnetic field enhancement space 105, and damage to a detection part caused by an electric field generated by the capacitors can be avoided.

Referring to fig. 6, in one embodiment, the magnetic field enhancement device 20 further includes a plurality of first conductive structures 519 and a plurality of second conductive structures 529. The plurality of first conductive structures 519 are disposed proximate the first end 103. Each of the first conductive structures 519 is disposed between two adjacent ones of the magnetic field enhancement assemblies 10. Both ends of each of the first conductive structures 519 are respectively connected to the second electrode layers 120 and the portions of the first electrode layers 110 of the adjacent two magnetic field enhancement assemblies 10 located in the first capacitance region 11. That is, one end of one of the first conductive structures 519 is connected to one of the second electrode layers 120 of the magnetic field enhancement assembly 10. The other end of one of the first conductive structures 519 is connected to a portion of the first electrode layer 110 of the adjacent magnetic field enhancing assembly 10 that is located in the first capacitive region 11.

On the side of the first end 103, the plurality of magnetic field enhancement assemblies 10 are connected in sequence by the plurality of first conductive structures 519. The induced current will sequentially pass through the second electrode layer 120, the two ends of the first resonance capacitor 911, the portion of the first electrode layer 110 located in the first capacitance region 11, the first conductive structure 519, the second electrode layer 120 adjacent to the magnetic field enhancing component 10, the two ends of the first resonance capacitor 911, the portion of the first electrode layer 110 located in the first capacitance region 11, the first conductive structure 519, etc. When equivalent to a circuit diagram, the plurality of first resonance capacitors 911 are serially connected one by one in sequence by the plurality of first conductive structures 519.

The plurality of second conductive structures 529 are disposed proximate the second end 104. Each of the second conductive structures 529 is disposed between two adjacent magnetic field enhancement assemblies 10. Both ends of each of the second conductive structures 529 are respectively connected to the third electrode layer 130 and the portions of the first electrode layer 110 of the adjacent two magnetic field enhancement assemblies 10 located in the second capacitance region 12. That is, one end of one of the second conductive structures 529 is connected to the third electrode layer 130 of one of the magnetic field enhancement assemblies 10. The other end of one of the second conductive structures 529 is connected to a portion of the first electrode layer 110 adjacent to the magnetic field enhancement assembly 10 that is located in the second capacitive region 12.

On the side of the second end 104, the plurality of magnetic field enhancement assemblies 10 are connected in sequence by the plurality of second conductive structures 529. The induced current will sequentially pass through the third electrode layer 130, the two ends of the second resonance capacitor 921, the portion of the first electrode layer 110 located in the second capacitance region 12, the second conductive structure 529, the third electrode layer 130 adjacent to the magnetic field enhancement assembly 10, the two ends of the second resonance capacitor 921, the portion of the first electrode layer 110 located in the second capacitance region 12, the second conductive structure 529, and so on. When equivalent to a circuit diagram, the plurality of second resonance capacitances 921 are serially connected one by one in sequence by the plurality of second conductive structures 529.

In one embodiment, the first conductive structure 519 and the second conductive structure 529 have a conductive function. The materials of the first conductive structure 519 and the second conductive structure 529 may be metal materials such as gold, silver, and copper.

Referring to fig. 7, in one embodiment, the magnetic field enhancement device 20 further includes a fifth diode 461, a sixth diode 462, and a fifth external capacitor 445. An anode of the fifth diode 461 is electrically connected to the second electrode layer 120. The cathode of the sixth diode 462 is electrically connected to the second electrode layer 120. One end of the fifth external capacitor 445 is electrically connected to the first electrode layer 110 in the first capacitor region 11, and the other end of the fifth external capacitor 445 is electrically connected to the cathode of the fifth diode 461 and the anode of the sixth diode 462, respectively.

In MRI systems, to enhance the magnetic field strength of human feedback signals during the radio frequency receive phase. In the radio frequency transmission phase of an MRI system, the magnetic field energy in the transmission phase is more than 1000 times of the magnetic field energy in the receiving phase. The induced voltage is between tens of volts and hundreds of volts during the transmit phase. The induced voltage in the receiving stage is less than 1V.

The fifth diode 461 and the sixth diode 462 are connected in anti-parallel. In the radio frequency transmitting stage, the radio frequency coil transmits radio frequency transmitting signals, and the field intensity of the magnetic field is larger. The induced voltage generated by the magnetic field enhancing assembly 10 is relatively large. The voltage applied across the fifth diode 461 and the sixth diode 462 is positively and negatively alternated. The applied voltage exceeds the turn-on voltage of the fifth diode 461 and the sixth diode 462, and the fifth diode 461 and the sixth diode 462 are turned on. The fifth external capacitor 445 is connected in parallel with the first resonant capacitor 911, and generates parallel resonance, so that the circuit is in a high-resistance state. During the radio frequency signal transmitting stage, almost no current flows between two adjacent magnetic field enhancement assemblies 10. The first resonant capacitor 911 is disconnected from the two adjacent magnetic field enhancement assemblies 10, and no current passes through the first resonant capacitor 911, and is in a detuned state. The magnetic field generated by the magnetic field enhancement device 20 is weakened, so that the influence of the magnetic field enhancement device 20 on the magnetic field in the transmission stage of the radio frequency signal is reduced, the artifact of the detected image is reduced, and the definition of the detected image is improved.

In the radio frequency receiving stage, the detection part transmits a feedback signal, and the field intensity of the magnetic field is smaller. The magnetic field enhancing assembly 10 produces a small induced voltage. The applied voltage cannot reach the turn-on voltage of the fifth diode 461 and the sixth diode 462, and the fifth diode 461 and the sixth diode 462 are not turned on. The first resonant capacitors 911 are electrically connected to two adjacent magnetic field enhancing members 10, respectively, and a current flows. The magnetic field enhancement device 20 is in a resonant state and acts to enhance the magnetic field.

In one embodiment, the magnetic field enhancement device 20 further includes a sixth external capacitor 4451, a first external diode 4611, and a second external diode 4622. The connection relationship between the sixth external capacitor 4451, the first external diode 4611 and the second external diode 4622 and the second resonant capacitor 921 is the same as the connection relationship between the fifth diode 461, the sixth diode 462 and the fifth external capacitor 445 and the first resonant capacitor 911, and the working principle is the same, and the description of the above embodiments can be referred to.

In the stage of transmitting the radio frequency signal, the second resonant capacitors 921 are disconnected from the two adjacent magnetic field enhancement assemblies 10, and no current passes through the second resonant capacitors, so that the second resonant capacitors are in a detuned state. The magnetic field generated by the magnetic field enhancement device 20 is weakened, so that the influence of the magnetic field enhancement device 20 on the magnetic field in the transmission stage of the radio frequency signal is reduced, the artifact of the detected image is reduced, and the definition of the detected image is improved. In the rf receiving stage, the second resonant capacitors 921 are electrically connected to two adjacent magnetic field enhancing members 10, respectively, and a current flows through them. The magnetic field enhancement device 20 is in a resonant state and acts to enhance the magnetic field.

Referring to fig. 8, in one embodiment, the magnetic field enhancement device 20 further includes a first depletion MOS transistor 231 and a second depletion MOS transistor 232. The source electrode of the first depletion MOS tube 231 is electrically connected to the first electrode layer 110 in the first capacitance region 11, and the gate electrode and the drain electrode of the first depletion MOS tube 231 are electrically connected. The gate and drain of the second depletion MOS transistor 232 are electrically connected. The gate and drain of the second depletion MOS transistor 232 are electrically connected to the gate and drain of the first depletion MOS transistor 231. One end of the first resonant capacitor 911 is electrically connected to the source of the second depletion MOS transistor 232. The other end of the first resonant capacitor 911 is electrically connected to the second electrode layer 120.

The first depletion MOS tube 231 and the second depletion MOS tube 232 are connected in reverse series, so that the first electrode layer 110 and the second electrode layer 120 can be controlled to be disconnected in a radio frequency transmitting stage and connected in a radio frequency receiving stage. The first depletion MOS tube 231 and the second depletion MOS tube 232 are connected in reverse series, so that the MRI apparatus can adapt to an alternating current environment. The first depletion MOS tube 231 and the second depletion MOS tube 232 are connected in reverse series, so that it is ensured that one of the first depletion MOS tube 231 and the second depletion MOS tube 232 is turned off in the radio frequency emission stage, and the circuit where the first resonance capacitor 911 is located is in open circuit and is not electrically connected with the second electrode layer 120 and the first electrode layer 110.

The first depletion MOS tube 231 and the second depletion MOS tube 232 have the characteristics of low voltage conduction and high voltage cut-off. And, the pinch-off voltage of the first depletion MOS transistor 231 and the second depletion MOS transistor 232 at room temperature is about 1V, and the turn-off time and the recovery time are both in nanosecond order. The radio frequency transmitting phase and the radio frequency receiving phase in the MRI apparatus have a difference of several tens of milliseconds to several thousands of milliseconds in time sequence, so that the first depletion type MOS tube 231 and the second depletion type MOS tube 232 can be rapidly turned on and off. The radio frequency power of the radio frequency transmit phase and the radio frequency receive phase differ by 3 orders of magnitude. The induced voltage in the coil during the radio frequency transmit phase is between a few V and a few hundred V, with specific values being dependent on the chosen sequence and flip angle.

In the radio frequency emission stage, the induced voltage is larger, the first depletion type MOS tube 231 and the second depletion type MOS tube 232 are in an off state, and the circuit where the first resonant capacitor 911 is located is in an off state and is not electrically connected to the second electrode layer 120 and the first electrode layer 110. The magnetic field enhancing means 20 is in a detuned state. No current is present in the magnetic field enhancing means 20 and no induced magnetic field is generated which would interfere with the radio frequency. In the rf receiving stage, the first depletion MOS 231 is turned on with the second depletion MOS 232, the circuit in which the first resonant capacitor 911 is located is in a turned-on state, and two ends of the circuit are electrically connected to the second electrode layer 120 and the first electrode layer 110 respectively. The magnetic field enhancement device 20 is capable of assuming a resonant state, greatly enhancing the signal field, enhancing the image signal-to-noise ratio.

In one embodiment, the magnetic field enhancement device 20 further includes a third depletion MOS tube 2311 and a fourth depletion MOS tube 2321. The source of the third depletion MOS transistor 2311 is electrically connected to the first electrode layer 110 in the first capacitance region 11. The gate and the drain of the third depletion MOS transistor 2311 are electrically connected. The gate and the drain of the fourth depletion MOS transistor 2321 are electrically connected. The gate and drain of the fourth depletion MOS transistor 2321 are electrically connected to the gate and drain of the third depletion MOS transistor 2311. One end of the second resonance capacitor 921 is electrically connected to the source of the fourth depletion MOS transistor 2321. The other end of the second resonance capacitor 921 is electrically connected to the third electrode layer 130.

The connection relationship between the third depletion MOS 2311, the fourth depletion MOS 2321 and the second resonant capacitor 921 is the same as the connection relationship between the first depletion MOS 231, the second depletion MOS 232 and the first resonant capacitor 911, and the working principle is the same, which can be seen in the above embodiment.

Through the third depletion MOS tube 2311, the fourth depletion MOS tube 2321, the connection relation of the second resonance capacitor 921, the first depletion MOS tube 231, the second depletion MOS tube 232 and the first resonance capacitor 911 form a symmetrical structure, a magnetic field can be further made to be more uniform and symmetrical, and imaging is facilitated.

In one embodiment, the third electrode layer 130 is not collinear with the second electrode layer 120. The third electrode layer 130 and the second electrode layer 120 are respectively disposed on geometric diagonals of the first surface 101.

Referring to fig. 9, in one embodiment, the present application provides a magnetic field enhancement device 20. The magnetic field enhancement device 20 includes a plurality of magnetic field enhancement assemblies 10. Each of the magnetic field enhancement assemblies 10 includes a first dielectric layer 100, a first electrode layer 110. The first dielectric layer 100 has a first end 103 and a second end 104 disposed opposite each other. The first dielectric layer 100 also has a first surface 101 extending from the first end 103 to the second end 104. The first surface 101 comprises a first capacitive area 11, a conductive area 13 and a second capacitive area 12 in a direction from the first end 103 to the second end 104. The conductive region 13 is located between the first capacitive region 11 and the second capacitive region 12. The first capacitive area 11 is near the first end 103. The second capacitive area 12 is near the second end 104.

The first electrode layer 110 is disposed on the first surface 101. The first electrode layer 110 extends from the first end 103 to the second end 104. The first electrode layer 110 covers the first surface 101. Each of the magnetic field enhancement assemblies 10 extends from the first end 103 to the second end 104.

Referring to fig. 10, the plurality of magnetic field enhancing assemblies 10 are spaced apart. The plurality of magnetic field enhancing members 10 enclose a magnetic field enhancing space 105.

The magnetic field enhancement device 20 further comprises a plurality of first resonance capacitances 911 and a plurality of second resonance capacitances 921. The plurality of first resonant capacitors 911 are disposed proximate the first end 103. Each of the first resonant capacitors 911 is disposed between two adjacent ones of the magnetic field enhancement assemblies 10. The two ends of the first resonant capacitor 911 are electrically connected to the first electrode layers 110 of the adjacent two magnetic field enhancing assemblies 10 located in the first capacitor region 11, respectively. That is, one end of the first resonance capacitor 911 is electrically connected to the first electrode layer 110 of one of the magnetic field enhancement members 10 located at the first capacitance region 11. The other end of the first resonance capacitor 911 is electrically connected to the first electrode layer 110 of the adjacent one of the magnetic field enhancement assemblies 10 located in the first capacitance region 11.

On the side of the first end 103, the plurality of magnetic field enhancement assemblies 10 are connected by the plurality of first resonant capacitors 911. When the magnetic field enhancement device 20 is placed in a magnetic field environment, an induced current is generated. On the first end 103 side, the induced current sequentially passes through the portion of the first electrode layer 110 located in the first capacitance region 11, the two ends of the first resonance capacitor 911, the portion of the first electrode layer 110 located in the first capacitance region 11 adjacent to the magnetic field enhancing component 10, the two ends of the first resonance capacitor 911, and so on. Referring to fig. 4, when equivalent to a circuit diagram, the plurality of first resonant capacitors 911 are sequentially connected in series one by one.

The plurality of second resonant capacitors 921 is disposed proximate the second end 104. Each of the second resonance capacitances 921 is disposed between two adjacent magnetic field enhancement assemblies 10. Both ends of the second resonance capacitor 921 are electrically connected to the first electrode layers 110 of the adjacent two magnetic field enhancement members 10 located in the second capacitance region 12, respectively. That is, one end of the second resonance capacitor 921 is electrically connected to the first electrode layer 110 of one of the magnetic field enhancing members 10 located in the second capacitance region 12. The other end of the second resonance capacitor 921 is electrically connected to the first electrode layer 110 of the adjacent one of the magnetic field enhancing members 10 located in the second capacitance region 12.

On the side of the second end 104, the plurality of magnetic field enhancing members 10 are connected by the plurality of second resonance capacitors 921. When the magnetic field enhancement device 20 is placed in a magnetic field environment, an induced current is generated. On the second end 104 side, the induced current sequentially passes through the portion of the first electrode layer 110 located in the second capacitance region 12, the two ends of the second resonance capacitor 921, the portion of the first electrode layer 110 located in the second capacitance region 12 adjacent to the magnetic field enhancing component 10, the two ends of the second resonance capacitor 921, and so on. Referring to fig. 4, when equivalent to a circuit diagram, the plurality of second resonance capacitors 921 are sequentially connected in series one by one.

The first electrode layer 110 covers the first surface 101, and no parallel plate capacitor is formed. When the plurality of magnetic field enhancement members 10 are connected and placed in a magnetic field environment, the plurality of first resonance capacitors 911 are sequentially connected in series one by one. The plurality of second resonance capacitors 921 are sequentially connected in series one by one.

Referring to fig. 11, in one embodiment, the magnetic field enhancement device 20 further includes a plurality of third conductive structures 539 and a plurality of fourth conductive structures 549. The plurality of third conductive structures 539 is disposed proximate the first end 103. The fourth plurality of conductive structures 549 is disposed proximate the second end 104.

In one embodiment, the third conductive structure 539 and the fourth conductive structure 549 have a conductive function. The third conductive structure 539 and the fourth conductive structure 549 may be made of metal materials such as gold, silver, copper, etc.

Referring to fig. 12, each third conductive structure 539 is disposed on a surface of each first electrode layer 110 away from the first dielectric layer 100. One of the third conductive structures 539 is disposed corresponding to one of the magnetic field enhancing assemblies 10. Two ends of each first resonant capacitor 911 are respectively electrically connected to two adjacent third conductive structures 539. That is, one end of one of the first resonant capacitors 911 is electrically connected to one of the third conductive structures 539. The other end of one of the first resonant capacitors 911 is electrically connected to an adjacent one of the third conductive structures 539. When equivalent to a circuit diagram, the plurality of first resonance capacitors 911 are sequentially connected in series through the plurality of third conductive structures 539.

Each of the fourth conductive structures 549 is disposed on a surface of each of the first electrode layers 110 remote from the first dielectric layer 100. One of the fourth conductive structures 549 is disposed corresponding to one of the magnetic field enhancement assemblies 10. Both ends of each second resonance capacitor 921 are electrically connected to two adjacent fourth conductive structures 549, respectively. That is, one end of one of the second resonance capacitors 921 is electrically connected to one of the fourth conductive structures 549. The other end of one of the second resonance capacitors 921 is electrically connected to an adjacent one of the fourth conductive structures 549. When equivalent to a circuit diagram, the plurality of second resonance capacitors 921 are sequentially connected in series through the plurality of fourth conductive structures 549.

Referring to fig. 13, in one embodiment, the magnetic field enhancement device 20 further includes a first inductor 241, a third diode 213, and a fourth diode 214. One end of the first inductor 241 is electrically connected to one end of the first resonant capacitor 911. An anode of the third diode 213 is electrically connected to the other end of the first resonance capacitor 911. The cathode of the third diode 213 is electrically connected to the other end of the first inductor 241. The cathode of the fourth diode 214 is electrically connected to the other end of the first resonant capacitor 911. An anode of the fourth diode 214 is electrically connected to the other end of the first inductor 241.

The third diode 213 and the fourth diode 214 are connected in anti-parallel. In the radio frequency transmitting stage, the radio frequency coil transmits radio frequency transmitting signals, and the field intensity of the magnetic field is larger. The induced voltage generated by the magnetic field enhancing assembly 10 is relatively large. The voltages applied across the third diode 213 and the fourth diode 214 alternate in opposite directions. The applied voltage exceeds the turn-on voltage of the third diode 213 and the fourth diode 214, and the third diode 213 and the fourth diode 214 are turned on. A third capacitor is connected in parallel with the first inductor 241, so that the circuit formed by the first resonant capacitor 911, the third diode 213, the fourth diode 214 and the first inductor 241 is in a high-resistance state. During the radio frequency signal transmitting stage, almost no current flows between two adjacent magnetic field enhancement assemblies 10. The first resonance capacitors 911 are disconnected from the first electrode layers 110 of the adjacent two magnetic field enhancement assemblies 10, respectively, and little current passes. The magnetic field generated by the magnetic field enhancement device 20 is weakened, so that the influence of the magnetic field enhancement device 20 on the magnetic field in the transmission stage of the radio frequency signal is reduced, the artifact of the detected image is reduced, and the definition of the detected image is improved.

In the radio frequency receiving stage, the detection part transmits a feedback signal, and the field intensity of the magnetic field is smaller. The magnetic field enhancing assembly 10 produces a small induced voltage. The applied voltage cannot reach the turn-on voltage of the third diode 213 and the fourth diode 214, and the third diode 213 and the fourth diode 214 are not turned on. The first resonant capacitors 911 are electrically connected to the first electrode layers 110 of the adjacent two magnetic field enhancement assemblies 10, respectively, and a current flows. The magnetic field enhancement device 20 is in a resonant state and acts to enhance the magnetic field.

In one embodiment, the magnetic field enhancement device 20 further includes a seventh diode 2131, an eighth diode 2141, and a second inductor 2411. The connection relationship between the seventh diode 2131, the eighth diode 2141, and the second inductor 2411 and the second resonant capacitor 921 are the same as the connection relationship between the first inductor 241, the third diode 213, and the fourth diode 214 and the first resonant capacitor 911, respectively, and the operation principle is the same, and reference may be made to the description of the above embodiments. During the rf generation phase, the second resonant capacitors 921 are disconnected from the first electrode layers 110 of the adjacent two magnetic field enhancement assemblies 10, respectively, and no current passes through them, and are in a detuned state. In the rf receiving stage, the second resonant capacitors 921 are electrically connected to the first electrode layers 110 of the adjacent two magnetic field enhancement assemblies 10, respectively, and a current flows through them. The magnetic field enhancement device 20 is in a resonant state and acts to enhance the magnetic field.

Referring to fig. 14, in one embodiment, the present application provides a magnetic field enhancement device 20. The magnetic field enhancement device 20 includes a plurality of magnetic field enhancement assemblies 10. Each of the magnetic field enhancement assemblies 10 includes a first dielectric layer 100, a first electrode layer 110, a second electrode layer 120, and a fourth electrode layer 140. The first dielectric layer 100 has a first end 103 and a second end 104 disposed opposite each other. The first dielectric layer 100 has oppositely disposed first and second surfaces 101, 102 extending from the first end 103 to the second end 104.

The first surface 101 comprises a first capacitive area 11, a conductive area 13 and a second capacitive area 12. The conductive region 13 is located between the first capacitive region 11 and the second capacitive region 12. The first capacitive area 11 is near the first end 103. The second capacitive area 12 is near the second end 104. The first electrode layer 110 is disposed on the first surface 101, extends from the first end 103 to the second end 104, and covers the first surface 101.

The second electrode layer 120 is disposed on the second surface 102. The second electrode layer 120 is located in the second capacitance region 12. The orthographic projection of the second electrode layer 120 on the first dielectric layer 100 is located in the orthographic projection of the first electrode layer 110 on the first dielectric layer 100, forming a second structural capacitor 152.

The fourth electrode layer 140 is disposed on the second surface 102. The fourth electrode layer 140 is spaced apart from the second electrode layer 120. The fourth electrode layer 140 is located in the first capacitance region 11. The fourth electrode layer 140 forms a first structural capacitance 151 in the front projection of the first dielectric layer 100 in the front projection of the first electrode layer 110 in the first dielectric layer 100.

Each of the magnetic field enhancement assemblies 10 extends from the first end 103 to the second end 104. The plurality of magnetic field enhancement assemblies 10 are spaced apart and surround to form a magnetic field enhancement space 105.

Referring to fig. 15, in the first capacitance region 11, the first electrode layers 110 of two adjacent magnetic field enhancement assemblies 10 are connected to the fourth electrode layer 140.

When the magnetic field enhancement device 20 is placed in a magnetic field environment, an induced current is generated. On the first end 103 side, two adjacent first structural capacitors 151 are connected to the fourth electrode layer 140 through the first electrode layer 110. The induced current sequentially passes through the first structure capacitors 151 one by one. When equivalent to a circuit diagram, the plurality of first structural capacitors 151 are sequentially connected in series one by one.

Referring to fig. 16, in the second capacitance region 12, the first electrode layers 110 of two adjacent magnetic field enhancement assemblies 10 are connected to the second electrode layer 120.

When the magnetic field enhancement device 20 is placed in a magnetic field environment, an induced current is generated. On the second end 104 side, two adjacent second structure capacitors 152 are connected through the first electrode layer 110 and the second electrode layer 120. The induced current will sequentially pass through the second structure capacitors 152 one by one. When equivalent to a circuit diagram, the plurality of second structural capacitors 152 are serially connected one by one in sequence.

When the plurality of magnetic field enhancement assemblies 10 are connected and placed in a magnetic field environment, the plurality of first structural capacitors 151 are sequentially connected in series one by one. The plurality of second structure capacitors 152 are sequentially connected in series one by one. The magnetic field enhancement means 20 may enhance the magnetic field when the operating frequency of the high-field or ultra-high-field MRI system (3T and above) is the same as the resonance frequency of the magnetic field enhancement means 20.

Since capacitance is inversely proportional to frequency, in high-field or ultra-high-field MRI systems (3T and above), the frequency is relatively large, which may make the equivalent capacitance of a structure formed by connecting multiple conventional magnetic field enhancing components relatively small. However, the plurality of first structural capacitors 151 are sequentially connected in series one by one, so that the equivalent capacitance formed by the plurality of first structural capacitors 151 becomes smaller. The plurality of second structure capacitors 152 are sequentially connected in series one by one, so that an equivalent capacitance formed by the plurality of second structure capacitors 152 becomes smaller. The plurality of second structural capacitors 152 and the plurality of first structural capacitors 151 may form a structure with a larger capacitance value, so that the resonance frequency of the magnetic field enhancing device 20 fluctuates less, and the stability of the resonance frequency is improved, which is more suitable for high-field MRI.

In one embodiment, the magnetic field enhancement device 20 further includes a plurality of fifth conductive structures 559 and a plurality of sixth conductive structures 569. The plurality of first structure capacitors 151 are sequentially connected in series through the plurality of fifth conductive structures 559. The plurality of second structure capacitors 152 are sequentially connected in series through the plurality of sixth conductive structures 569. The plurality of fifth conductive structures 559 and the plurality of sixth conductive structures 569 have a conductive function. The materials of the fifth conductive structures 559 and the sixth conductive structures 569 may be made of metal materials such as gold, silver, copper, etc.

Referring to fig. 17, in one embodiment, the magnetic field enhancement device 20 further includes a first external capacitor 440, a first diode 431 and a second diode 432. Both ends of the first external capacitor 440 are electrically connected to the second electrode layer 120 and the portion of the first electrode layer 110 located in the second capacitor region 12, respectively. The anode of the first diode 431 is electrically connected to a portion of the first electrode layer 110 located in the second capacitance region 12. The cathode of the first diode 431 is electrically connected to the second electrode layer 120. The cathode of the second diode 432 is electrically connected to the portion of the first electrode layer 110 located in the second capacitance region 12. The anode of the second diode 432 is electrically connected to the second electrode layer 120.

It is understood that the turn-on voltage of the first diode 431 and the second diode 432 may be between 0 volt and 1 volt. In one embodiment, the turn-on voltage of the first diode 431 and the second diode 432 may be 0.8V. In the second capacitance region 12, the first diode 431 and the second diode 432 are respectively connected in series between the first electrode layer 110 and the second electrode layer 120, and the first diode 431 and the second diode 432 are reversely connected.

Due to the alternating nature of radio frequency. The induced voltage generated by the first electrode layer 110 and the second electrode layer 120 is also an alternating voltage. In the radio frequency emission phase, the turn-on voltage of the first diode 431 and the second diode 432 has been exceeded due to the voltage difference between the first electrode layer 110 and the second electrode layer 120. Therefore, whichever of the first electrode layer 110 and the second electrode layer 120 has a higher voltage, one of the first diode 431 and the second diode 432 is always in an on state. Thus electrically connecting the first electrode layer 110 and the second electrode layer 120. The first external capacitor 440 is shorted. The magnetic field enhancing means 20 is in a detuned state.

In the rf receiving stage, since the voltage difference between the first electrode layer 110 and the second electrode layer 120 is smaller than the turn-on voltage of the first diode 431 and the second diode 432. Therefore, the first diode 431 and the second diode 432 are in a non-conductive state regardless of which of the first electrode layer 110 and the second electrode layer 120 is high in voltage. The magnetic field enhancing means 20 is in resonance.

In one embodiment, in the first capacitor region 11, the first electrode layer 110 and the fourth electrode layer 140 may be electrically connected to the first external capacitor 440, the first diode 431 and the second diode 432, respectively, and the connection relationships are the same. The magnetic field enhancement device 20 forms a symmetrical structure at the first end 103 and the second end 104, which is more beneficial to the uniform distribution of the magnetic field and improves the imaging quality of the MRI apparatus.

In one embodiment, the element capacitance in the above embodiment may be a fixed capacitance or a tuning capacitance. When the frequency of the rf coil is determined, the element capacitance may be selected to be a suitable fixed capacitance, so that the fixed capacitance is matched with other structures of capacitance and element capacitance, so that the resonant frequency of the magnetic field enhancing device 20 is equal to the frequency of the rf coil, and the magnetic field enhancing effect is further achieved. When the frequency of the radio frequency coil is not determined, the element capacitance may be an adjustable capacitance. By adjusting the adjustable capacitance, the resonant frequency is adjusted so that the magnetic field enhancing means 20 is adapted to different working environments.

Referring to fig. 18 and 19, in one embodiment, the magnetic field enhancement device 20 further includes a cylindrical support structure 50. The cylindrical support structure 50 has two spaced-apart opposed third and fourth ends 51, 53. The cylindrical support structure 50 has inner and outer surfaces 521, 522 disposed in spaced opposition. The inner surface 521 encloses a detection space 509. The plurality of magnetic field enhancing assemblies 10 are spaced apart from the outer surface 522. The magnetic field enhancing assembly 10 extends along the third end 51 toward the fourth end 53.

The detection space 509 may be adapted to accommodate a detection site. The detection part can be an arm, a leg, an abdomen and the like. The plurality of magnetic field enhancement assemblies 10 are equally spaced apart to improve the uniformity of the local magnetic field. A plurality of the magnetic field enhancement assemblies 10 may be equally spaced from the outer surface 522 of the cylindrical support structure 50.

In one embodiment, a plurality of spacing structures 550 are spaced around the outer surface 522 of the cylindrical support structure 50. Each of the magnetic field enhancement assemblies 10 corresponds to the spacing structure 550 of the third end 51 and the spacing structure 550 of the fourth end 53, respectively, in a direction along the third end 51 to the fourth end 53. One of the magnetic field enhancing assemblies 10 is secured by the spacing structures 550 at both ends of the third and fourth ends 51, 53, thereby securing the magnetic field enhancing assembly 10 to the cylindrical support structure 50.

In one embodiment, the limiting structure 550 may be a through slot. The through slots may be used for insertion of the magnetic field enhancing assembly 10. The two through slots respectively limit two ends of the magnetic field enhancement assembly 10. The magnetic field enhancing assembly 10 may be secured to the outer surface 522 of the cylindrical support structure 50 by the spacing structure 550.

In one embodiment, the magnetic field enhancement device 20 may include 12 of the magnetic field enhancement assemblies 10 equally spaced about the axis on the outer surface 522 of the cylindrical support structure 50.

In one embodiment, the length of the first electrode layer 110 is 100mm and the width of the first electrode layer 110 is 15mm in the direction from the first end 103 to the second end 104. The width of the first conductive structure 519, the second conductive structure 529, the third conductive structure 539, the fourth conductive structure 549 is 10mm in the direction from the first end 103 to the second end 104. The diameter of the magnetic field enhancing means 20 is 100mm.

Referring to fig. 20, in one embodiment, the conventional structure and the magnetic field enhancement device of the present application are applied to a 7T MRI system, and it can be seen that for the same length of the magnetic field enhancement device, the capacitance value required by the conventional structure is 0.6pF, which is far smaller than the capacitance value of the current common capacitor, in order to meet the requirement of the 7T MRI system. However, the magnetic field enhancement device 20 of the present application requires a capacitance of 6pF, which is a common capacitance for the market. The resonance frequency of the conventional structure is lowered by 75.5MHz when the capacitance value is increased by 1pF, compared to the capacitance value of 0.6pF required for the conventional structure. However, the resonant frequency of the magnetic field enhancing device 20 of the present application is reduced by only 22.8MHz. Therefore, the structure of the magnetic field enhancement device 20 of the present application is more stable in the high frequency band. The magnetic field enhancement device 20 has a relatively slow rate of change of resonant frequency with capacitance, making tuning of the structure easier to operate and more suitable for high-field MRI. Referring to fig. 21, it can be seen that the magnetic field enhancement device 20 of the present application still has a highly uniform magnetic field distribution at the high frequency band.

In the description of the present specification, reference to the terms "some embodiments," "other embodiments," "desired embodiments," and the like, means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description. The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the claims. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.

Claims

1. A magnetic field enhancement device, comprising:

A plurality of magnetic field enhancement components (10), each of the magnetic field enhancement components (10) comprising:

A first dielectric layer (100) having a first end (103) and a second end (104) arranged opposite to each other, the first dielectric layer (100) further having a first surface (101) extending from the first end (103) to the second end (104), the first surface (101) comprising a first capacitance region (11), a conduction region (13) and a second capacitance region (12), the conduction region (13) being located between the first capacitance region (11) and the second capacitance region (12), the first capacitance region (11) being close to the first end (103), and the second capacitance region (12) being close to the second end (104);

A first electrode layer (110) is disposed on the first surface (101) and extends from the first end (103) to the second end (104);

A second electrode layer (120) is arranged on the first surface (101) and located in the first capacitor region (11), the second electrode layer (120) being spaced apart from a portion of the first electrode layer (110) located in the first capacitor region (11);

A third electrode layer (130) is arranged on the first surface (101) and is located in the second capacitor region (12), and the third electrode layer (130) is spaced apart from a portion of the first electrode layer (110) located in the second capacitor region (12);

Each of the magnetic field enhancement components (10) extends from the first end (103) to the second end (104), and the plurality of magnetic field enhancement components (10) are arranged at intervals and surround a magnetic field enhancement space (105);

A plurality of first resonant capacitors (911) are arranged near the first end (103), one first resonant capacitor (911) is arranged corresponding to one of the magnetic field enhancement components (10), one end of each of the first resonant capacitors (911) is electrically connected to the second electrode layer (120), the other end of each of the first resonant capacitors (911) is electrically connected to a portion of the first electrode layer (110) located in the first capacitor region (11), and the second electrode layers (120) of two adjacent magnetic field enhancement components (10) are connected to portions of the first electrode layer (110) located in the first capacitor region (11);

A plurality of second resonant capacitors (921) are arranged near the second end (104), one second resonant capacitor (921) is arranged corresponding to one of the magnetic field enhancement components (10), one end of each of the second resonant capacitors (921) is electrically connected to the third electrode layer (130), the other end of each of the second resonant capacitors (921) is electrically connected to a portion of the first electrode layer (110) located in the second capacitor region (12), and the third electrode layers (130) of two adjacent magnetic field enhancement components (10) are connected to portions of the first electrode layer (110) located in the second capacitor region (12).

2. The magnetic field enhancement device according to claim 1, characterized in that, in the first capacitor area (11), the first resonant capacitor (911) is arranged on the first surface (101);

In the second capacitor region (12), the second resonant capacitor (921) is arranged on the first surface (101).

3. The magnetic field enhancement device according to claim 1, further comprising:

A plurality of first conductive structures (519) are arranged close to the first end (103), and each of the first conductive structures (519) is arranged between two adjacent magnetic field enhancement components (10);

Two ends of each of the first conductive structures (519) are respectively connected to the second electrode layers (120) of two adjacent magnetic field enhancement components (10) and a portion of the first electrode layer (110) located in the first capacitor region (11);

A plurality of second conductive structures (529) are arranged close to the second end (104), and each of the second conductive structures (529) is arranged between two adjacent magnetic field enhancement components (10);

Two ends of each second conductive structure (529) are respectively connected to the third electrode layer (130) of two adjacent magnetic field enhancement components (10) and a portion of the first electrode layer (110) located in the second capacitor region (12).

4. The magnetic field enhancement device according to claim 1, further comprising:

a fifth diode (461), wherein an anode of the fifth diode (461) is electrically connected to the second electrode layer (120);

a sixth diode (462), wherein a cathode of the sixth diode (462) is electrically connected to the second electrode layer (120); and

A fifth external capacitor (445), one end of the fifth external capacitor (445) is electrically connected to the first electrode layer (110) located in the first capacitor region (11), and the other end of the fifth external capacitor (445) is electrically connected to the cathode of the fifth diode (461) and the anode of the sixth diode (462), respectively.

5. The magnetic field enhancement device according to claim 1, further comprising:

A first depletion-type MOS transistor (231), wherein a source of the first depletion-type MOS transistor (231) is electrically connected to the first electrode layer (110) located in the first capacitor region (11), and a gate and a drain of the first depletion-type MOS transistor (231) are electrically connected;

A second depletion-type MOS transistor (232), wherein the gate and drain of the second depletion-type MOS transistor (232) are electrically connected, and are also electrically connected to the gate and drain of the first depletion-type MOS transistor (231);

One end of the first resonant capacitor (911) is electrically connected to the source of the second depletion-type MOS transistor (232), and the other end of the first resonant capacitor (911) is electrically connected to the second electrode layer (120).

6. A magnetic field enhancement device, comprising:

A first electrode layer (110) is disposed on the first surface (101), extends from the first end (103) to the second end (104), and covers the first surface (101);

a plurality of first resonant capacitors (911) arranged near the first end (103), each of the first resonant capacitors (911) being arranged between two adjacent magnetic field enhancement components (10), and two ends of the first resonant capacitor (911) being electrically connected to the first electrode layers (110) located in the first capacitor region (11) of the two adjacent magnetic field enhancement components (10);

A plurality of second resonant capacitors (921) are arranged near the second end (104), each of the second resonant capacitors (921) is arranged between two adjacent magnetic field enhancement components (10), and the two ends of the second resonant capacitor (921) are respectively electrically connected to the first electrode layer (110) located in the second capacitor region (12) of the two adjacent magnetic field enhancement components (10).

7. The magnetic field enhancement device according to claim 6, further comprising:

A plurality of third conductive structures (539) are arranged near the first end (103), and each of the third conductive structures (539) is arranged on a surface of each of the first electrode layers (110) away from the first dielectric layer (100);

Two ends of each of the first resonant capacitors (911) are electrically connected to two adjacent third conductive structures (539) respectively;

a plurality of fourth conductive structures (549), arranged near the second end (104), and each of the fourth conductive structures (549) is arranged on a surface of each of the first electrode layers (110) away from the first dielectric layer (100);

Two ends of each of the second resonant capacitors (921) are electrically connected to two adjacent fourth conductive structures (549) respectively.

8. The magnetic field enhancement device according to claim 6, further comprising:

A first inductor (241), one end of the first inductor (241) being electrically connected to one end of the first resonant capacitor (911);

a third diode (213), wherein an anode of the third diode (213) is electrically connected to the other end of the first resonant capacitor (911), and a cathode of the third diode (213) is electrically connected to the other end of the first inductor (241);

A fourth diode (214), wherein a cathode of the fourth diode (214) is electrically connected to the other end of the first resonant capacitor (911), and an anode of the fourth diode (214) is electrically connected to the other end of the first inductor (241).

9. A magnetic field enhancement device, comprising:

A first dielectric layer (100) having a first end (103) and a second end (104) arranged opposite to each other, the first dielectric layer (100) having a first surface (101) and a second surface (102) arranged opposite to each other, extending from the first end (103) to the second end (104), the first surface (101) comprising a first capacitance region (11), a conduction region (13) and a second capacitance region (12), the conduction region (13) being located between the first capacitance region (11) and the second capacitance region (12), the first capacitance region (11) being close to the first end (103), and the second capacitance region (12) being close to the second end (104);

A second electrode layer (120) is arranged on the second surface (102) and is located in the second capacitor region (12); an orthographic projection of the second electrode layer (120) on the first dielectric layer (100) is located in an orthographic projection of the first electrode layer (110) on the first dielectric layer (100), forming a second structural capacitor (152);

a fourth electrode layer (140) disposed on the second surface (102), spaced apart from the second electrode layer (120), and located in the first capacitance region (11); an orthographic projection of the fourth electrode layer (140) on the first dielectric layer (100) being located in an orthographic projection of the first electrode layer (110) on the first dielectric layer (100), forming a first structural capacitor (151);

In the first capacitor region (11), the first electrode layer (110) of two adjacent magnetic field enhancement components (10) are connected to the fourth electrode layer (140);

In the second capacitor region (12), the first electrode layer (110) and the second electrode layer (120) of two adjacent magnetic field enhancement components (10) are connected.

10. The magnetic field enhancement device according to claim 9, further comprising:

A first external capacitor (440), wherein two ends of the first external capacitor (440) are respectively electrically connected to the second electrode layer (120) and a portion of the first electrode layer (110) located in the second capacitor region (12);

a first diode (431), wherein an anode of the first diode (431) is electrically connected to a portion of the first electrode layer (110) located in the second capacitor region (12), and a cathode of the first diode (431) is electrically connected to the second electrode layer (120);

A second diode (432), wherein a cathode of the second diode (432) is electrically connected to a portion of the first electrode layer (110) located in the second capacitor region (12), and an anode of the second diode (432) is electrically connected to the second electrode layer (120).