CN216083063U

CN216083063U - Radio frequency coil and magnetic resonance imaging equipment

Info

Publication number: CN216083063U
Application number: CN202121975501.3U
Authority: CN
Inventors: 方福衣; 徐烽; 罗威; 沈振华
Original assignee: Shanghai United Imaging Healthcare Co Ltd
Current assignee: Shanghai United Imaging Healthcare Co Ltd
Priority date: 2021-08-20
Filing date: 2021-08-20
Publication date: 2022-03-18
Anticipated expiration: 2031-08-20

Abstract

The utility model provides a radio frequency coil applied to magnetic resonance imaging equipment, which comprises a plurality of annular coil units, wherein the plurality of coil units are circumferentially distributed around a preset axis and are sequentially connected; a plurality of feeding ports corresponding to the coil units one to one, the feeding ports being disposed on the corresponding coil units; a plurality of capacitors, at least one of the capacitors coupled to each of the coil units. As configured above, the circuit characteristics of the coil unit are adjusted by providing the capacitance; compared with the prior art, the number of channels of the radio frequency coil can be increased to be more than four by arranging the plurality of coil units and the corresponding plurality of feed ports, so that the radio frequency coil can be applied to a high-field or ultrahigh-field transmitting coil; in addition, the cooperation of multiple coil units and multiple feed ports may also improve shimming of the radio frequency coil.

Description

Radio frequency coil and magnetic resonance imaging equipment

Technical Field

The utility model relates to the technical field of medical instruments, in particular to a radio frequency coil and magnetic resonance imaging equipment.

Background

In MR (Magnetic Resonance Imaging) or PET-MR (positron emission Tomography-Magnetic Resonance Imaging) systems, there are radio-frequency coils, which comprise a transmit coil and a receive coil, or a radio-frequency coil which is both transmitting and receiving. In the prior art, multi-channel parallel transmission or a polarization change mode is often adopted to improve the nonuniformity of a radio frequency field so as to improve the detection precision. For example, in high-field magnetic resonance systems, local birdcage transmit coils, or array volume transmit coils, are often employed.

Taking the body transmitting coil as an example, the body transmitting coil is used as the radio frequency front end of the magnetic resonance device and is responsible for transmitting and receiving magnetic resonance signals. Currently, a birdcage-type transmit coil (hereinafter "birdcage coil") is often selected as the body transmit coil due to its high unloaded uniformity. In the prior art, a birdcage coil generally adopts orthogonal excitation of two feed ports, the two excitations have a spatial difference of 90 °, theoretically, the feed ports of the excitation form are not coupled with each other or have a small degree of mutual coupling, so that the birdcage coil is limited to the excitation form of the birdcage coil, the number of the feed ports of the birdcage coil is at most four, and the difference between two adjacent feed ports is 90 °, that is, four feed ports are uniformly distributed on 360 ° of the circumference. Therefore, the number of the passages of the birdcage coil is four (corresponding to the feed ports one to one), the number of the passages is small, the requirement of the number of the passages of the body transmitting coil in the high-field or ultrahigh-field parallel transmitting technology cannot be met, and the application range of the birdcage coil is limited.

In addition, as the frequency of the high field or the ultrahigh field is increased, the influence of the medium effect is more obvious, even some medium shadows appear, and the image quality of the magnetic resonance imaging is influenced, the method for improving the problem is generally to improve the shimming performance of the radio frequency coil, and the birdcage coil is limited to be used in a high-field or ultrahigh-field transmitting coil because the radio frequency fields of the channels are highly similar and the shimming freedom is lower.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a radio frequency coil and a magnetic resonance imaging device, which aim to solve the problem that the radio frequency coil in the prior art is limited to be used in a high-field or ultra-high-field transmitting coil due to the fact that the number of channels is small.

To solve the above technical problem, according to an aspect of the present invention, there is provided a radio frequency coil applied to a magnetic resonance imaging apparatus, the radio frequency coil including:

the coil units are circumferentially distributed around a preset axis and are sequentially connected;

a plurality of feeding ports corresponding to the coil units one to one, the feeding ports being disposed on the corresponding coil units;

a plurality of capacitors, at least one of the capacitors coupled to each of the coil units.

Optionally, at least one of the capacitors on each of the coil units is an adjustable capacitor.

Optionally, each coil unit is coupled with a plurality of capacitors, at least a first part of the capacitors are frequency modulation capacitors, and at least a second part of the capacitors are frequency modulation capacitors.

Optionally, the sum of capacitance values of all the frequency modulation capacitors on each coil unit is a frequency modulation capacitance value, and the frequency modulation capacitance values of at least two coil units are different.

Optionally, the coil unit has a first leg edge and a second leg edge that are oppositely arranged along the direction of the preset axis, and the first leg edge and the second leg edge are respectively coupled with at least one frequency modulation capacitor.

Optionally, the coil unit has a first leg side and a second leg side which are oppositely arranged along the direction of the preset axis; the feeding port is arranged on the first leg edge or the second leg edge of the corresponding coil unit.

Optionally, the feeding ports corresponding to all the coil units are located on the same side along the direction of the preset axis.

Optionally, the first leg edges of all the coil units are located on one side of the direction of the preset axis, and the second leg edges of all the coil units are located on the other side of the direction of the preset axis; the first leg edges of all the coil units are sequentially connected in the circumferential direction of the radio frequency coil to form a first closed loop, and/or the second leg edges of all the coil units are sequentially connected in the circumferential direction of the radio frequency coil to form a second closed loop.

Optionally, two adjacent coil units share one edge to form a common edge, a plurality of common edges of the radio frequency coil are circumferentially distributed around the preset axis, and at least two adjustable coupling capacitors are coupled to each common edge of the radio frequency coil.

Based on another aspect of the present invention, the present invention also provides a magnetic resonance imaging apparatus comprising:

the radio frequency coil as described above;

the coil exchanging module is internally provided with a transmitting channel and a receiving channel and comprises a plurality of switching devices in one-to-one correspondence with the coil units, and the switching devices are used for controlling the corresponding feed ports of the coil units to be connected into the transmitting channel or the receiving channel.

In summary, in the radio frequency coil and the magnetic resonance imaging apparatus provided by the present invention, the radio frequency coil includes a plurality of annular coil units, and the plurality of coil units are circumferentially distributed around a preset axis and sequentially connected; a plurality of feeding ports corresponding to the coil units one to one, the feeding ports being disposed on the corresponding coil units; a plurality of capacitors, at least one of the capacitors coupled to each of the coil units. As configured above, the circuit characteristics of the coil unit are adjusted by providing the capacitance; compared with the prior art, the number of channels of the radio frequency coil can be increased to be more than four by arranging the plurality of coil units and the corresponding plurality of feed ports, so that the radio frequency coil can be applied to a high-field or ultrahigh-field transmitting coil; in addition, the cooperation of multiple coil units and multiple feed ports may also improve shimming of the radio frequency coil.

Drawings

It will be appreciated by those skilled in the art that the drawings are provided for a better understanding of the utility model and do not constitute any limitation to the scope of the utility model. Wherein:

FIG. 1 is a schematic diagram of a radio frequency coil in accordance with one embodiment of the present invention;

FIG. 2 is an expanded view of a radio frequency coil in accordance with one embodiment of the present invention;

FIG. 3 is an equivalent schematic diagram of a coil unit of the radio frequency coil of one embodiment of the present invention;

fig. 4 is a schematic diagram of a coil swapping module according to an embodiment of the present invention.

In the drawings:

a LOOP-coil unit; 11-a first leg edge; 110 — first closed loop; 12-a second leg edge; 120-a second closed loop; 13-common edge;

20-a frequency modulation capacitor; 30-a feed port; 40-a coupling capacitance; a-a preset axis.

Detailed Description

To further clarify the objects, advantages and features of the present invention, a more particular description of the utility model will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is to be noted that the drawings are in greatly simplified form and are not to scale, but are merely intended to facilitate and clarify the explanation of the embodiments of the present invention. Further, the structures illustrated in the drawings are often part of actual structures. In particular, the drawings may have different emphasis points and may sometimes be scaled differently.

As used in this application, the singular forms "a", "an" and "the" include plural referents, the term "or" is generally employed in a sense including "and/or," the terms "a" and "an" are generally employed in a sense including "at least one," the terms "at least two" are generally employed in a sense including "two or more," and the terms "first", "second" and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit to the number of technical features indicated. Thus, features defined as "first", "second" and "third" may explicitly or implicitly include one or at least two of the features, "one end" and "the other end" and "proximal end" and "distal end" generally refer to the corresponding two parts, which include not only the end points, but also the terms "mounted", "connected" and "connected" should be understood broadly, e.g., as a fixed connection, as a detachable connection, or as an integral part; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. Furthermore, as used in the present invention, the disposition of an element with another element generally only means that there is a connection, coupling, fit or driving relationship between the two elements, and the connection, coupling, fit or driving relationship between the two elements may be direct or indirect through intermediate elements, and cannot be understood as indicating or implying any spatial positional relationship between the two elements, i.e., an element may be in any orientation inside, outside, above, below or to one side of another element, unless the content clearly indicates otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The utility model provides a radio frequency coil and a magnetic resonance imaging device, which aim to solve the problem that the radio frequency coil in the prior art is limited to be used in a high-field or ultrahigh-field transmitting coil due to the fact that the number of channels is small.

The radio frequency coil of the present embodiment is described below with reference to the drawings.

Referring to fig. 1 and fig. 2, fig. 1 is a schematic diagram of a radio frequency coil according to an embodiment of the present invention, fig. 2 is an expanded view of a radio frequency coil according to an embodiment of the present invention, the radio frequency coil of the present embodiment is applied to a magnetic resonance imaging apparatus, and the radio frequency coil includes: a plurality of annular coil units LOOP (fig. 2 is used for exemplary illustration, and only 3 coil units LOOP are listed), the plurality of coil units LOOP are circumferentially distributed around a preset axis a and are sequentially connected, that is, the plurality of coil units LOOP are circumferentially arranged around the preset axis a (the circumference perpendicular to the axis a) and are sequentially connected end to end, and are substantially cylindrical, which can be further understood as that the plurality of coil units are sequentially arranged on a cylindrical surface with the preset axis a as a central axis (the radius of the cylindrical surface can be set according to actual conditions); a plurality of feeding ports 30 corresponding to the coil units LOOP one by one, wherein the feeding ports 30 are disposed on the corresponding coil units LOOP, and the feeding ports 30 are used for transmitting a driving signal (such as a radio frequency signal) to the radio frequency coil under the action of an external device, so that the radio frequency coil generates a radio frequency field; a plurality of capacitors, at least one of said capacitors coupled to each of said coil units LOOP, the capacitors being configured to change a circuit characteristic of the coil units LOOP.

It should be noted that the ring-shaped coil unit LOOP of the present embodiment does not limit the specific shape of the coil unit LOOP, and may be, for example, a circular ring, an elliptical ring, or a polygonal ring (a square ring is exemplified in fig. 2), and those skilled in the art can configure the LOOP according to actual requirements. The number of the coil units LOOP in this embodiment is not particularly limited, and considering the structural size of the rf coil, the uniformity of the rf field, and the difficulty in tuning the rf coil, the number of the coil units LOOP is preferably an even number (for example, fig. 1 of this embodiment exemplifies 4 coil units LOOP). Generally, the greater the number of coil units LOOP, the better the uniformity of the radio frequency field, but it is prone to cause splitting of the resonant mode, and the tuning process becomes more complicated and more costly. Preferably, a plurality of the coil units LOOP are uniformly arranged circumferentially around the preset axis a to improve uniformity of the radio frequency field.

Generally, the radio frequency coil is enclosed on a medical scanning tube, a scanning cavity is formed inside the scanning tube and used for accommodating an examination object (such as a human body), the radio frequency coil is used for sending a driving signal (such as a radio frequency signal), forming a radio frequency field, and completing scanning imaging under the coordination of other magnetic resonance related instruments. Specifically, the rf coil has a plurality of feeding ports 30 corresponding to the coil units LOOP one to one, the feeding ports 30 are disposed on the corresponding coil units LOOP, and the rf coil can be connected to a control system through the feeding ports 30, and the control system can include an FPGA (Field-Programmable Gate Array) control unit, a DAC (Digital to analog converter), an rf amplifier and a power divider, which are connected in sequence, wherein an rf sequence transmitted by the FPGA control unit is sequentially converted into an analog signal by the DAC, amplified by the rf amplifier, and then converted into a driving signal by the power divider, and sent to the plurality of feeding ports 30 of the rf coil, so as to drive the rf coil to generate a circularly polarized Field. As can be seen from the above, the rf coil is formed by sequentially coupling a plurality of coil units LOOP, and is provided with the corresponding feed ports 30 and the capacitors for changing the circuit characteristics, compared with the prior art, the number of channels of the rf coil LOOP can be increased by more than four, so that the rf coil can be applied to a high-field or ultra-high-field transmitting coil; in addition, the matching of the plurality of coil units LOOP and the plurality of feed ports 30 can also improve the shimming of the radio frequency coil and improve the imaging effect of magnetic resonance.

For further explanation, referring to fig. 3, fig. 3 is an equivalent schematic diagram of a single coil unit according to an embodiment of the present invention, and fig. 3 exemplarily identifies a current flow direction when one of the coil units LOOP operates. It should be noted that the current flowing direction between the plurality of coil units LOOP may be the same or different from each other, depending on the magnitude and phase of the supply current of each coil unit LOOP, and those skilled in the art can understand the prior art and will not be described herein.

For example, the current flowing through the coil unit LOOP is distributed in a discrete form, and the current corresponding to the nth coil unit LOOP is approximately:

J_leg(n)＝J₀cos(2πn/N)

wherein the content of the first and second substances,

J₀a constant current value for initial setting; j. the design is a square_leg(n) is the current on the nth coil unit LOOP; n is the total number of coil units LOOP; n is a natural number greater than 1.

For example, when N is 12, the rf coils shown in fig. 1 are sequentially counted clockwise and respectively denoted as 1 st coil unit LOOP, 2 nd coil unit LOOP, … …, and 12 th coil unit LOOP. As can be seen from the above formula, the current in the 1 st coil unit LOOP and the current in the 6 th coil unit LOOP are the largest, and accordingly, different current source signals can be provided for different coil units LOOP. It is understood that each feeding port 30 can be connected to a different rf amplifier, and the amplitude and phase of the driving signal generated by each rf amplifier can be set independently, i.e. the amplitude and phase of the driving signal of each coil unit LOOP can be set independently.

In this embodiment, each coil unit LOOP is coupled with a plurality of capacitors, wherein at least a first portion of the capacitors is the frequency modulation capacitor 20, and at least a second portion of the capacitors is the coupling capacitor 40. It can be understood that the tuning capacitor 20 is used to adjust the resonant frequency of the rf coil, and the tuning coupling capacitor 40 is used to adjust the coupling degree between the coil units LOOP.

Further, defining the sum of the capacitance values of all the frequency modulation capacitors 20 on each coil unit LOOP as a frequency modulation capacitance value; wherein, the frequency modulation capacity values of at least two coil units LOOP are not equal. It can be understood that the frequency modulation capacitor 20 is used to adjust the resonant frequency of the rf coil, and the change of the frequency can be realized by the operator configuring the capacitance value of the frequency modulation capacitor 20 in advance; the tuning capacitance value in this embodiment specifically refers to the sum of the capacitance values of all the tuning capacitors 20 on the single coil unit LOOP. It should be noted that the frequency modulation capacity values of at least two coil units LOOP are not equal, and here, the positional relationship of the coil units LOOP with different frequency modulation capacity values is not limited, for example, the coil units LOOP may be adjacent in sequence, or may be oppositely arranged along the radial direction of the radio frequency coil; in addition, due to practical limitations, the term "different tuning capacity values" is not intended to be construed as absolute inequality, i.e., the difference between two tuning capacity values is not equal to zero, and it is to be understood that the tuning capacity values of the two coil units LOOP are not equal to each other when the difference between the two tuning capacity values is not less than a threshold value.

As can be seen from the above, the rf coil is formed by coupling a plurality of coil units LOOP in sequence, and generally, when the adjustment is performed without using the coupling adjustment component (or the coupling adjustment effect of the coupling adjustment component is not ideal), the coupling degree between the coil units LOOP is relatively strong, including the coupling degree between two adjacent coil units LOOP and the coupling degree between non-adjacent coil units LOOP, which may cause the accuracy of the signal to deviate during the magnetic resonance examination process, thereby affecting the scanning result. Considering that the coil units LOOP have a certain bandwidth, and can be normally excited in a certain frequency range (for example, between-10 MHz to +10MHz), by configuring that the frequency modulation capacity values of at least two coil units LOOP are not equal, strong mutual coupling between the coil units LOOP can be avoided, the decoupling effect of the radio frequency coil is improved, the independence of the coil units LOOP is better, the magnetic resonance imaging effect is better, and the judgment of pathological causes of an examination object by an operator is facilitated. Here, "decoupling" refers to weakening the coupling degree between the coils, which can theoretically make the coupling degree between the coil units LOOP weak close to 0. In addition to the reduction of the coupling degree between the coil units LOOP with different tuning capacitance values, the coupling degree of the other coil units LOOP can be reduced to some extent. Preferably, the frequency modulation capacity values of each coil unit LOOP are not equal, so as to further improve the decoupling effect of the radio frequency coil. In addition, the tuning capacitor 20 can also adjust the resonance frequency of the corresponding coil unit LOOP, thereby adjusting (correcting) the resonance frequency of the radio frequency coil.

Regarding the specific arrangement form of the frequency-modulation capacitors 20, for example, the coil unit LOOP of the present embodiment may be configured to have a first leg edge 11 and a second leg edge 12 oppositely arranged along the direction of the preset axis a, and at least one of the frequency-modulation capacitors 20 is coupled to the first leg edge 11 and the second leg edge 12, respectively.

Preferably, at least one of the frequency-modulating capacitors 20 on the coil unit LOOP is an adjustable capacitor, that is, the capacitance value of the capacitor can be adjusted. With the above configuration, on one hand, an operator can conveniently adjust the capacitance value of the corresponding frequency modulation capacitor 20, so that the frequency modulation capacitance value of the corresponding coil unit LOOP is changed; on the other hand, the adjustable capacitor can be adjusted to adjust the LOOP resonant frequency of different coil units, so that the resonant frequency of the radio frequency coil is accurately corrected. The capacitance value of the adjustable capacitor can be adjusted mechanically, for example, specifically, a rotatable adjusting part is provided on the adjustable capacitor, an operator can be connected with the adjusting part by an adaptive tool, and the adjusting part is driven by the tool to rotate, and further, the relative distance or the relative area of the metal sheet inside the adjustable capacitor can be changed by the rotation of the adjusting part, so as to change the capacitance value of the adjustable capacitor. Preferably, the adjustable capacitors on the coil unit LOOP are located on the same side along the predetermined axis a (e.g., both located on the upper side or the lower side as shown in fig. 2), so that the operator can conveniently adjust the capacitors on the same side, thereby improving efficiency.

In the present embodiment, regarding the specific arrangement form of the feeding port 30, the present embodiment may configure that the coil unit LOOP has a first leg edge 11 and a second leg edge 12 oppositely arranged along the direction of the preset axis a; the feeding port 30 is disposed on the first leg edge 11 or the second leg edge 12 of the corresponding coil unit LOOP. The transmission of the driving signal (radio frequency signal) to the radio frequency coil is realized by connecting the feeding port 30 with an external control system.

Preferably, the feeding ports 30 corresponding to all the coil units LOOP are located on the same side along the direction of the preset axis a, and the feeding ports 30 corresponding to all the coil units LOOP are located in the circumferential direction perpendicular to the direction of the preset axis a, that is, the feeding ports 30 are sequentially arranged along the circumferential direction of the radio frequency coil. For example, the feeding ports 30 corresponding to all the coil units LOOP are located on the upper side or the lower side in fig. 2, which can reduce the interference of signals on one hand and is also beneficial to the convenience of cable connection for operators on the other hand.

In a preferred embodiment, the first leg edges 11 of all the coil units LOOP are located at one side of the direction of the preset axis a, and the second leg edges 12 of all the coil units LOOP are located at the other side of the direction of the preset axis a; the first leg edges 11 of all the coil units LOOP are sequentially connected along the circumferential direction of the radio frequency coil to form a first closed LOOP 110, and/or the second leg edges 12 of all the coil units LOOP are sequentially connected along the circumferential direction of the radio frequency coil to form a second closed LOOP 120. The configuration can make the structure of the radio frequency coil more compact, reduce the structure size and make the radio frequency coil beautiful. It is understood that the specific shape of the first closed loop 110 and the second closed loop 120 is not limited, and is determined by the shape of the corresponding first leg edge 11 and the corresponding second leg edge 12, for example, when the first leg edge 11 is a straight line, the first closed loop 110 is a substantially regular polygonal loop, and when the first leg edge 11 is a circular arc, the first closed loop 110 is a substantially circular loop; the second closed loop 120 is similar to the first closed loop 110 and will not be described herein. Preferably, the first closed loop 110 and the second closed loop 120 exist at the same time, so that the structure size can be further reduced.

Of course, in other embodiments, the first leg edges 11 of all the coil units LOOP may not be connected in sequence along the circumferential direction of the radio frequency coil, and are independent of each other; and/or the second leg edges 12 of all the coil units LOOP are not connected in sequence along the circumferential direction of the radio frequency coil and are independent of each other.

As a more preferable embodiment, two adjacent coil units LOOP share one edge to form a common edge 13, and a plurality of common edges 13 of the rf coil are circumferentially distributed around the preset axis a. Therefore, the structural size of the radio frequency coil can be reduced, and the whole structure is more compact.

Regarding the specific arrangement of the tunable coupling capacitor 40 of the present embodiment, it is preferable that at least two tunable coupling capacitors 40 are coupled to each common side 13 of the rf coil. The common edge 13 has a certain width (specifically, a width along the circumferential direction of the rf coil), and the common edge 13 is provided with the decoupling capacitor 40, which is used to further weaken (remove) the coupling degree between two adjacent coil units LOOP, and compared with the prior art that the area of the coil units LOOP needs to be increased in the overlapping decoupling manner between two adjacent coils, the embodiment configures the decoupling capacitor 40 on the common edge 13, which can not increase the area of the coil units LOOP, save materials, and make the shimming performance of the rf coil better. In addition, by adopting the decoupling mode that the common edge 13 is coupled with the adjustable coupling capacitor 40, other decoupling structures (such as a decoupling circuit and external decoupling equipment) are not required to be added.

Preferably, at least one of the adjustable coupling capacitors 40 coupled to the common side 13 is an adjustable capacitor, i.e. the capacitance value of the capacitor can be adjusted. With the above configuration, an operator can easily adjust the capacitance of the corresponding decoupling capacitor 40, so that the capacitance of the total decoupling capacitor 40 of the corresponding coil unit LOOP is changed, thereby further improving the coupling degree between two adjacent coil units LOOP. The capacitance value of the adjustable capacitor can be adjusted mechanically, for example, specifically, a rotatable adjusting part is provided on the adjustable capacitor, an operator can be connected with the adjusting part by an adaptive tool, and the adjusting part is driven by the tool to rotate, and further, the relative distance or the relative area of the metal sheet inside the adjustable capacitor can be changed by the rotation of the adjusting part, so as to change the capacitance value of the adjustable capacitor. Preferably, the adjustable capacitors on the coil units LOOP are located on the same side along the predetermined axis a, for example, the adjustable coupling capacitors 40 on the upper sides of all the common sides 13 in fig. 2 are adjustable capacitors, or the adjustable coupling capacitors 40 on the lower sides of all the common sides 13 are adjustable capacitors, so that an operator can conveniently adjust the capacitors on the same side, and efficiency is improved.

The inventor has found that if only one tuning capacitor 40 is disposed on the common side 13, a capacitor with a large volume and a high withstand voltage is required, which is inconvenient for the structural design of the rf coil. On the other hand, the effect of decoupling the adjacent other coil unit LOOP is not so desirable. And at least two coupling capacitors 40 are adopted, so that the capacitors with smaller capacitance values can be adopted, the volume of the capacitors is dispersed, the distribution of the capacitors is more uniform, and the decoupling effect on the adjacent coil units LOOP is improved.

It should be noted that the first leg edge 11, the second leg edge 12 and the common edge 13 mentioned above with respect to the coil unit LOOP of the present embodiment may be made of a conductive material such as copper sheet, for example. The first leg edge 11, the second leg edge 12 and the common edge 13 may be integrally formed or may be separately formed and then sequentially connected. Optionally, the copper sheet has a set width, and one or more slots extending in a direction parallel to the preset axis a or in a circumferential direction of the preset axis a are disposed on the copper sheet, and the eddy current effect on the coil unit LOOP can be reduced by disposing the slots.

As is known in the art, radio frequency coils are key components of MRI equipment and may be capable of transmitting or both transmitting and receiving. The radio frequency coil in the embodiment has both a transmitting function and a receiving function, specifically, when the radio frequency coil is in a transmitting state, a radio frequency pulse is transmitted to the examination object to generate a radio frequency field, so that some atoms (such as hydrogen atoms) containing single protons in the body of the examination object absorb energy to generate resonance; the radio frequency coil receives MR signals (similar to a radio wave) formed by atomic resonance in the body of the examination object in a receiving state. The radio frequency coil of the present embodiment may further be a body transmit line coil.

When the rf coil has both transmitting and receiving functions, the present embodiment may adjust the state of the rf coil by configuring a coil exchanging module connected to the rf coil, specifically, please refer to fig. 4, where fig. 4 is a schematic diagram of the coil adjusting module according to an embodiment of the present invention, a transmitting channel and a receiving channel (RX) are built in the coil exchanging module of the present embodiment, the coil exchanging module includes a plurality of switching devices (T/R Switch) corresponding to the coil units LOOP one to one, and the switching devices are used to control the feeding ports 30 of the corresponding coil units LOOP to access the transmitting channel or the receiving channel. Generally, the feeding port 30 is used for accessing the transmitting channel and the receiving channel through a power line, and in this embodiment, a switching device may be disposed on the power line, and the switching device controls the power line to be closed with the transmitting channel or the receiving channel, so as to implement whether the feeding port 30 is connected with the transmitting channel or the receiving channel.

In an exemplary embodiment, taking an example that the rf coil has 8 coil units LOOP, the feeding port 30 of each coil unit LOOP is connected to the coil exchanging module through a correspondingly disposed power line, the exchanging module has one-to-one corresponding number of switching devices (T/R Switch) to the feeding ports 30, that is, each switching device acts on one coil unit LOOP, and fig. 4 illustrates numbers 1 to 8, each number corresponds to one coil unit LOOP (feeding port 30). Specifically, the switch device may be a single-pole double-throw switch, and when the feed port 30 is connected to a Radio Frequency Power Amplifier (RFPA) by switching, the radio frequency coil may be in a transmitting state at this time; when the switch is switched to connect the feeding port 30 with the receiving channel (RX), the rf coil is in a receiving state. It should be noted that fig. 4 only schematically indicates the connection relationship between the feeding port 30 and the switching device corresponding to the number 1, and the power amplifier (RFPA1) and the receiving channel (RX1), and the connection between the feeding port 30 and the switching device corresponding to other numbers can be obtained accordingly, and this embodiment will not be described again. In addition, the transmission channel is usually externally connected to a radio frequency power amplifier, and the radio frequency power amplifier "RFPA" identified in fig. 4 may be equivalent to the transmission channel understood as described in the present embodiment.

Based on the radio frequency coil, the embodiment also provides a magnetic resonance imaging apparatus, which includes the radio frequency coil. It should be noted that the magnetic resonance imaging apparatus herein may be, for example, an MR apparatus or a PET-MR apparatus, and the present invention is not limited thereto. Since the magnetic resonance imaging apparatus includes the radio frequency coil as described above, the magnetic resonance imaging apparatus has the advantages brought by the radio frequency coil, and the working principle and other structural components of the magnetic resonance imaging apparatus will not be explained in detail in this embodiment, which can be learned by those skilled in the art according to the prior art.

For example, in an exemplary embodiment, the magnetic resonance imaging apparatus includes a control system, a scanning cylinder, and the rf coil enclosed on the scanning cylinder, the control system may include an FPGA (Field-Programmable Gate Array) control unit, a Digital-to-analog conversion unit (DAC), an rf amplifier, and a power divider, which are connected in sequence, wherein the rf sequence transmitted by the FPGA control unit is sequentially converted into an analog signal by the Digital-to-analog conversion unit, amplified by the rf amplifier, and then converted into a driving signal by the power divider, and sent to the plurality of feeding ports 30 of the rf coil, so as to drive the rf coil to generate the circularly polarized Field.

The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art according to the above disclosure are within the scope of the present invention.

Claims

1. A radio frequency coil for use in a magnetic resonance imaging apparatus, comprising:

a plurality of annular coil units (LOOP) circumferentially distributed around a preset axis (a) and connected in sequence;

a plurality of feeding ports (30) in one-to-one correspondence with the coil units (LOOP), the feeding ports (30) being provided on the corresponding coil units (LOOP);

a plurality of capacitors (20, 40), at least one of said capacitors (20, 40) being coupled to each of said coil units (LOOP).

2. The radio frequency coil as set forth in claim 1, characterized in that at least one of the capacitances (20, 40) on each of the coil units (LOOP) is an adjustable capacitance.

3. The radio frequency coil as set forth in claim 1, wherein a plurality of said capacitors (20, 40) are coupled to each of said coil units (LOOP), at least a first portion of said capacitors (20, 40) being frequency modulated capacitors (20), and at least a second portion of said capacitors (20, 40) being frequency modulated capacitors (40).

4. A radio frequency coil according to claim 3, wherein the sum of the capacitance values of all the frequency-modulated capacitors (20) on each of the coil units (LOOP) is a frequency-modulated capacitance value, and the frequency-modulated capacitance values of at least two of the coil units (LOOP) are different.

5. A radio frequency coil as claimed in claim 3, wherein the coil unit (LOOP) has a first leg edge (11) and a second leg edge (12) arranged opposite to each other in the direction of the preset axis (a), the first leg edge (11) and the second leg edge (12) being coupled with at least one of the frequency-modulating capacitors (20), respectively.

6. The radio-frequency coil as set forth in claim 1, characterized in that the coil unit (LOOP) has a first leg edge (11) and a second leg edge (12) oppositely arranged in the direction of the preset axis (a); the feeding port (30) is provided on the first leg side (11) or the second leg side (12) of the corresponding coil unit (LOOP).

7. The radio-frequency coil as set forth in claim 6, characterized in that the respective feed ports (30) of all the coil elements (LOOP) are located on the same side in the direction of the preset axis (A).

8. The radio-frequency coil as set forth in claim 5 or 6, characterized in that the first leg edges (11) of all the coil units (LOOP) are located on one side of the direction of the preset axis (A), and the second leg edges (12) of all the coil units (LOOP) are located on the other side of the direction of the preset axis (A); wherein the first leg edges (11) of all the coil units (LOOP) are sequentially connected along the circumferential direction of the radio frequency coil to form a first closed LOOP (110), and/or the second leg edges (12) of all the coil units (LOOP) are sequentially connected along the circumferential direction of the radio frequency coil to form a second closed LOOP (120).

9. A radio frequency coil as claimed in claim 3, wherein two adjacent coil elements (LOOP) share a common side, a plurality of said common sides (13) of the radio frequency coil being circumferentially distributed around said predetermined axis (a), at least two of said tuning capacitors (40) being coupled to each common side (13) of the radio frequency coil.

10. A magnetic resonance imaging apparatus, characterized by comprising:

the radio frequency coil of any one of claims 1 to 7 or claim 9;

the coil exchanging module is internally provided with a transmitting channel and a receiving channel and comprises a plurality of switching devices which are in one-to-one correspondence with the coil units (LOOP), and the switching devices are used for controlling the corresponding feed ports (30) of the coil units (LOOP) to be connected into the transmitting channel or the receiving channel.