Radio frequency coil and magnetic resonance imaging device

Abstract

The application provides a radio frequency coil applied to a magnetic resonance imaging device, which comprises a plurality of loop-shaped coil units, the plurality of coil units are distributed in a circumferential direction around a preset axis and are sequentially connected; a plurality of feed ports corresponding to the coil units, the feed ports are arranged on the corresponding coil units; and a plurality of capacitors, at least one capacitor is coupled to each coil unit. Through the above configuration, the capacitors are arranged to adjust the circuit characteristics of the coil units; compared with the prior art, the plurality of coil units and the corresponding plurality of feed ports can increase the number of channels of the radio frequency coil to be greater than four, so that the radio frequency coil can be applied to a high-field or ultrahigh-field transmitting coil; in addition, the cooperation of the plurality of coil units and the plurality of feed ports can also improve the shimming of the radio frequency coil.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a radio frequency coil and a magnetic resonance imaging device. Background Technology

[0002] In MR (Magnetic Resonance Imaging) or PET-MR (Positron Emission Tomography-Magnetic Resonance Imaging) systems, there is a radio frequency (RF) coil, which includes a transmitting coil and a receiving coil, or an RF coil that performs both transmitting and receiving functions. Existing technologies often employ multi-channel parallel transmission or altered polarization to improve the inhomogeneity of the RF field, thereby enhancing detection accuracy. For example, in high-field MR systems, localized birdcage transmitting coils or array-type transmitting coils are commonly used.

[0003] Taking a bulk transmitter coil as an example, the bulk transmitter coil serves as the radio frequency front-end of a magnetic resonance imaging (MRI) device, responsible for transmitting and receiving MRI signals. Currently, birdcage-type transmitter coils (hereinafter referred to as "birdcage coils") are often chosen as bulk transmitter coils due to their high no-load uniformity. In existing technologies, birdcage coils generally employ orthogonal excitation from two feed ports, with the two excitations spatially separated by 90°. Theoretically, there is little or no coupling between the feed ports in this excitation form. Therefore, limited by this excitation form, the maximum number of feed ports for a birdcage coil is four, with a 90° gap between adjacent feed ports, meaning four feed ports are evenly distributed along a 360° circumference. Consequently, the birdcage coil has a maximum of four channels (corresponding one-to-one with the feed ports), a relatively small number that cannot meet the channel requirements for bulk transmitter coils in high-field or ultra-high-field parallel transmission technologies, thus limiting the application range of birdcage coils.

[0004] Furthermore, as the frequency of high or ultra-high fields increases, the influence of dielectric effects becomes more pronounced, and even some dielectric shadows may appear, affecting the image quality of magnetic resonance imaging. The common way to improve this problem is to improve the uniformity of the radio frequency coil. However, birdcage coils have low uniformity due to the high similarity of the radio frequency fields in the channels, which limits their use in high or ultra-high field transmitting coils. Summary of the Invention

[0005] The purpose of this invention is to provide a radio frequency coil and a magnetic resonance imaging device to solve the problem that the radio frequency coil in the prior art is limited to use in high field or ultra-high field transmitting coils due to the small number of channels.

[0006] To address the aforementioned technical problems, based on one aspect of the present invention, a radio frequency coil is provided for use in a magnetic resonance imaging device, the radio frequency coil comprising:

[0007] Multiple ring-shaped coil units are distributed circumferentially around a preset axis and connected sequentially.

[0008] Multiple power supply ports corresponding one-to-one with the coil unit, the power supply ports being disposed on the corresponding coil unit;

[0009] Multiple capacitors, with at least one capacitor coupled to each of the coil units.

[0010] Optionally, at least one of the capacitors on each of the coil units is an adjustable capacitor.

[0011] Optionally, each of the coil units is coupled with a plurality of capacitors, at least a first portion of the capacitors being frequency-modulated capacitors and at least a second portion of the capacitors being coupling capacitors.

[0012] Optionally, the sum of the capacitance values ​​of all the frequency modulation capacitors on each coil unit is the frequency modulation capacitance value, and the frequency modulation capacitance values ​​of at least two coil units are not equal.

[0013] Optionally, the coil unit has a first leg and a second leg arranged opposite to each other along the preset axis, and at least one of the frequency modulation capacitors is coupled to the first leg and the second leg, respectively.

[0014] Optionally, the coil unit has a first leg and a second leg arranged opposite to each other along the preset axis; the power supply port is disposed on the corresponding first leg or second leg of the coil unit.

[0015] Optionally, the feed ports corresponding to all the coil units are located on the same side along the direction of the preset axis.

[0016] 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; wherein, the first leg edges of all the coil units are sequentially connected along the circumference 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 along the circumference of the radio frequency coil to form a second closed loop.

[0017] Optionally, two adjacent coil units share a common edge to form a common edge, and multiple common edges of the RF coil are circumferentially distributed around the preset axis. At least two tuning capacitors are coupled to each common edge of the RF coil.

[0018] According to another aspect of the present invention, the present invention also provides a magnetic resonance imaging device, which includes a radio frequency coil as described above.

[0019] In summary, the radio frequency coil and magnetic resonance imaging device provided by this invention include a plurality of ring-shaped coil units, which are circumferentially distributed around a preset axis and connected sequentially; a plurality of feed ports corresponding one-to-one with each coil unit, the feed ports being disposed on the corresponding coil unit; and a plurality of capacitors, with at least one capacitor coupled to each coil unit. With the above configuration, the circuit characteristics of the coil units can be adjusted by setting capacitors. Compared to the prior art, by setting multiple coil units and corresponding multiple feed ports, the number of channels of the radio frequency coil can be increased to more than four, enabling the radio frequency coil to be applied in high-field or ultra-high-field transmission coils. Furthermore, the cooperation of multiple coil units and multiple feed ports can also improve the field uniformity of the radio frequency coil. Attached Figure Description

[0020] Those skilled in the art will understand that the accompanying drawings are provided to better understand the invention and do not constitute any limitation on the scope of the invention. Wherein:

[0021] Figure 1 This is a schematic diagram of a radio frequency coil according to an embodiment of the present invention;

[0022] Figure 2 This is an unfolded view of a radio frequency coil according to an embodiment of the present invention;

[0023] Figure 3 This is an equivalent schematic diagram of a coil unit of a radio frequency coil according to an embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of a coil switching module according to an embodiment of the present invention.

[0025] In the attached image:

[0026] LOOP - Coil unit; 11 - First leg edge; 110 - First closed loop; 12 - Second leg edge; 120 - Second closed loop; 13 - Common edge;

[0027] 20 - Frequency modulation capacitor; 30 - Power supply port; 40 - Coupling capacitor; A - Preset axis. Detailed Implementation

[0028] To make the objectives, advantages, and features of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to facilitate and clarify the explanation of the embodiments of this invention. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and may sometimes use different scales.

[0029] As used in this invention, the singular forms “a,” “an,” and “the” include plural objects; the term “or” is generally used to mean “and / or”; the term “a number” is generally used to mean “at least one”; and the term “at least two” is generally used to mean “two or more”. Furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as “first,” “second,” or “third” may explicitly or implicitly include one or at least two of that feature. “One end” and “the other end,” as well as “proximal end” and “distal end,” generally refer to two corresponding parts, including not only endpoints. The terms “installed,” “connected,” and “joined” should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral part; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or a connection within two elements or an interaction between two elements. Furthermore, as used in this invention, the phrase "one element is disposed on another element" generally only indicates that there is a connection, coupling, cooperation, or transmission relationship between the two elements, and the connection, coupling, cooperation, or transmission between the two elements can be direct or indirect through an intermediate element. It should not be construed as indicating or implying a spatial positional relationship between the two elements, i.e., one element can be located arbitrarily inside, outside, above, below, or to one side of the other element, unless otherwise explicitly stated. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0030] This invention provides a radio frequency coil and a magnetic resonance imaging device to solve the problem that the radio frequency coil in the prior art is limited to use in high field or ultra-high field transmitting coils due to the small number of channels.

[0031] The radio frequency coil of this embodiment will now be described with reference to the accompanying drawings.

[0032] Please see Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of a radio frequency coil according to an embodiment of the present invention. Figure 2This is an unfolded diagram of a radio frequency coil according to an embodiment of the present invention. The radio frequency coil of this embodiment is used in a magnetic resonance imaging device. The radio frequency coil includes: a plurality of loop-shaped coil units (LOOP). Figure 2 For illustrative purposes only, three coil units (LOOPs) are listed. Multiple coil units (LOOPs) are circumferentially distributed around a preset axis A and connected sequentially. That is, multiple coil units (LOOPs) are arranged circumferentially around the preset axis A (the circumferential direction perpendicular to axis A) and connected end-to-end, roughly forming a cylindrical shape. This can be further understood as multiple coil units arranged sequentially on a cylindrical surface with the preset axis A as the central axis (the radius of the cylindrical surface can be set according to actual conditions). Multiple feed ports 30 correspond one-to-one with each coil unit (LOOP). The feed ports 30 are located on the corresponding coil unit (LOOP) and are used to transmit drive signals (such as radio frequency signals) to the radio frequency coil under the action of an external device, thereby causing the radio frequency coil to generate a radio frequency field. Multiple capacitors are also included, with at least one capacitor coupled to each coil unit (LOOP). The capacitors are used to change the circuit characteristics of the coil unit (LOOP).

[0033] It should be noted that the loop coil unit LOOP in this embodiment is not limited to a specific shape; for example, it can be a circular ring, an elliptical ring, or a polygonal ring. Figure 2 The example shown is a regular quadrilateral ring, which can be configured according to actual needs by those skilled in the art. This embodiment does not impose a specific limit on the number of coil unit loops. Considering the structural dimensions of the RF coil, the uniformity of the RF field, and the difficulty of RF coil debugging, the number of coil unit loops is preferably an even number (such as in this embodiment). Figure 1 Four coil unit loops are demonstrated. Generally, the more coil unit loops there are, the better the uniformity of the radio frequency field, but it is prone to causing the resonant mode to split, making the tuning process more complex and costly. Preferably, the multiple coil unit loops are arranged circumferentially and uniformly around the preset axis A to improve the uniformity of the radio frequency field.

[0034] Typically, an RF coil is mounted around a medical scanning tube, forming a scanning cavity inside the tube to accommodate the object being examined (such as a human body). The RF coil transmits drive signals (such as RF signals) to generate a RF field, and completes the scanning imaging in conjunction with other MRI-related instruments. Specifically, the RF coil has multiple feed ports 30 corresponding one-to-one with coil unit LOOPs. The feed ports 30 are located on the corresponding coil unit LOOPs. The RF coil can be connected to a control system through the feed ports 30. This control system may include an FPGA (Field-Programmable Gate Array) control unit, a digital-to-analog converter (DAC), an RF amplifier, and a power divider connected in sequence. The 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 drive signal by the power divider, which is sent to the multiple feed ports 30 of the RF coil to drive the RF coil to generate a circularly polarized field. As can be seen above, the RF coil is formed by multiple coil units LOOP coupled to each other in sequence, and is provided with corresponding feed ports 30 and capacitors to change the circuit characteristics. Compared with the prior art, the number of channels of the RF coil LOOP can be increased to more than four, so that the RF coil can be used in high field or ultra-high field transmitting coils. In addition, the cooperation of multiple coil units LOOP and multiple feed ports 30 can also improve the field uniformity of the RF coil and enhance the imaging effect of magnetic resonance.

[0035] For further explanation, please refer to Figure 3 , Figure 3 This is an equivalent schematic diagram of a single coil unit according to an embodiment of the present invention. Figure 3 The current flow direction of one of the coil unit loops is illustrated exemplarily. It should be noted that the current flow direction among multiple coil unit loops can be the same or different from each other, depending on the amplitude and phase of the supply current of each coil unit loop, which can be understood by those skilled in the art based on existing technology, and will not be elaborated here.

[0036] 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:

[0037] J leg (n)=J0cos(2πn / N)

[0038] in,

[0039] J0 is the initially set constant current value; J leg(n) represents the current in the nth loop; N represents the total number of loops; and n is a natural number greater than 1.

[0040] For example, when N is 12, according to Figure 1 The RF coils shown are counted sequentially clockwise, denoted as the 1st coil unit LOOP, the 2nd coil unit LOOP, ..., the 12th coil unit LOOP. As shown in the formula above, the 1st and 6th coil unit LOOPs have the highest currents, and correspondingly, different current source signals can be provided to different coil unit LOOPs. It is understandable that each feed port 30 can be connected to a different RF amplifier, and the amplitude and phase of the drive signal generated by each RF amplifier can be set independently; that is, the amplitude and phase of the drive signal for each coil unit LOOP can be set independently.

[0041] In this embodiment, each coil unit LOOP is coupled with multiple capacitors, wherein at least the first part of the capacitors is a frequency modulation capacitor 20, and at least the second part of the capacitors is a coupling capacitor 40. Understandably, the frequency modulation capacitor 20 is used to adjust the resonant frequency of the RF coil, and the coupling capacitor 40 is used to adjust the degree of coupling between coil units LOOP.

[0042] Furthermore, the sum of the capacitance values ​​of all the frequency modulation capacitors 20 on each coil unit LOOP is defined as the frequency modulation capacitance value; wherein, the frequency modulation capacitance values ​​of at least two coil unit LOOPs are not equal. It is understood that the frequency modulation capacitors 20 are used to adjust the resonant frequency of the RF coil, and the frequency can be changed by the operator pre-configuring the capacitance values ​​of the frequency modulation capacitors 20; the frequency modulation capacitance value mentioned in this embodiment specifically refers to the sum of the capacitance values ​​of all the frequency modulation capacitors 20 on a single coil unit LOOP. It should be noted that the fact that the frequency modulation capacitance values ​​of at least two coil unit LOOPs are not equal does not restrict the positional relationship of coil unit LOOPs with unequal frequency modulation capacitance values; for example, they can be sequentially adjacent or arranged radially opposite each other along the RF coil. In addition, due to the limitations of practical applications, the unequal frequency modulation capacitance values ​​here should not be narrowly interpreted as absolute inequality, i.e., the difference between two frequency modulation capacitance values ​​is not equal to zero. It should be understood that the frequency modulation capacitance values ​​of the two coil unit LOOPs are unequal when the difference between the two frequency modulation capacitance values ​​is not less than a threshold value.

[0043] As mentioned above, a radio frequency (RF) coil is composed of multiple coil units linked together sequentially. Generally, without adjustment components for coupling (or when the coupling adjustment components are not effective), the coupling between coil unit loops is quite strong, including the coupling between adjacent coil unit loops and the coupling between non-adjacent coil unit loops. This can lead to deviations in signal accuracy during MRI examinations, thus affecting the scan results. Considering that coil unit loops have a certain bandwidth and can be excited normally within a certain frequency range (e.g., -10MHz to +10MHz), by configuring at least two coil unit loops with unequal frequency modulation capacitance values, strong mutual coupling between coil unit loops can be avoided, improving the decoupling effect of the RF coil. This results in better independence of the coil unit loops, leading to better MRI results and facilitating the surgeon's assessment of the pathological cause of the examined object. Here, "decoupling" refers to reducing the coupling between coils, theoretically reducing the coupling between coil unit loops to near zero. In addition to reducing the coupling between coil unit loops with unequal frequency modulation capacitance values, it can also reduce the coupling of other coil unit loops to some extent. Preferably, the frequency modulation capacitance value of each coil unit LOOP is different to further improve the decoupling effect of the RF coil. In addition, the frequency modulation capacitor 20 can also adjust the resonant frequency of the corresponding coil unit LOOP, thereby adjusting (correcting) the resonant frequency of the RF coil.

[0044] Regarding the specific arrangement of the frequency modulation capacitor 20, for example, the coil unit LOOP in this embodiment can be configured to have a first leg 11 and a second leg 12 arranged opposite to each other along the preset axis A, with at least one frequency modulation capacitor 20 coupled to the first leg 11 and the second leg 12 respectively.

[0045] Preferably, at least one of the frequency modulation capacitors 20 on the coil unit LOOP is an adjustable capacitor, meaning its capacitance value can be adjusted. With this configuration, on the one hand, the operator can easily adjust the capacitance value of the corresponding frequency modulation capacitor 20, thereby changing the frequency modulation capacitance of the corresponding coil unit LOOP; on the other hand, the adjustable capacitor can be adjusted to achieve adjustment of the resonant frequency of different coil unit LOOPs, thus enabling precise correction of the resonant frequency of the RF coil. Regarding the adjustment of the adjustable capacitor's capacitance value, it can be done mechanically. Specifically, the adjustable capacitor is equipped with a rotatable adjusting component. The operator can connect to this adjusting component using a suitable tool and drive it to rotate. The rotation of the adjusting component can change the relative distance or relative area of ​​the metal plates inside the adjustable capacitor, thereby changing the capacitance value of the adjustable capacitor. Preferably, the adjustable capacitors on the coil unit LOOP are located on the same side along a preset axis A (e.g., all located on...). Figure 2(as shown above or below), which allows the operator to easily adjust on the same side, improving efficiency.

[0046] In this embodiment, regarding the specific arrangement of the power supply port 30, the coil unit LOOP can be configured to have a first leg 11 and a second leg 12 arranged opposite to each other along the preset axis A; the power supply port 30 is disposed on the corresponding first leg 11 or second leg 12 of the coil unit LOOP. The power supply port 30 is connected to an external control system to transmit a drive signal (RF signal) to the RF coil.

[0047] Preferably, the feed ports 30 corresponding to all the coil unit LOOPs are located on the same side along the direction of the preset axis A, and the feed ports 30 corresponding to all the coil unit LOOPs are located in the circumferential direction perpendicular to the direction of the preset axis A, that is, multiple feed ports 30 are arranged sequentially along the circumference of the RF coil. For example, the feed ports 30 corresponding to all the coil unit LOOPs are located on the same side along the direction of the preset axis A. Figure 2 Placing it on the upper or lower side can reduce signal interference and also make it easier for operators to connect cables.

[0048] In a preferred embodiment, the first leg 11 of all the above-mentioned coil unit LOOPs is located on one side of the direction of the preset axis A, and the second leg 12 of all the coil unit LOOPs is located on the other side of the direction of the preset axis A; wherein, the first leg 11 of all the coil unit LOOPs are sequentially connected along the circumference of the RF coil to form a first closed loop 110, and / or, the second leg 12 of all the coil unit LOOPs are sequentially connected along the circumference of the RF coil to form a second closed loop 120. This configuration makes the structure of the RF coil more compact, reduces the structural size, and makes the RF coil more aesthetically pleasing. It is understood that the specific shapes of the first closed loop 110 and the second closed loop 120 are not limited, and are determined according to the shapes of the corresponding first leg 11 and the corresponding second leg 12. For example, when the first leg 11 is straight, the first closed loop 110 is approximately a regular polygonal ring; when the first leg 11 is arc-shaped, the first closed loop 110 is approximately a circular ring; the second closed loop 120 is similar to the first closed loop 110, and will not be described in detail here. Preferably, the first closed loop 110 and the second closed loop 120 exist simultaneously, which can further reduce the structural size.

[0049] Of course, in some other embodiments, the first leg 11 of all coil units LOOP may not be connected sequentially along the circumference of the radio frequency coil, and may be independent; and / or, the second leg 12 of all coil units LOOP may not be connected sequentially along the circumference of the radio frequency coil, and may be independent.

[0050] In a preferred embodiment, two adjacent coil units (LOOPs) share a common edge 13, and multiple common edges 13 of the RF coil are circumferentially distributed around the preset axis A. This reduces the structural size of the RF coil, making the overall structure more compact.

[0051] Regarding the specific arrangement of the tuning capacitors 40 in this embodiment, it is preferred that at least two tuning capacitors 40 are coupled on each common side 13 of the RF coil. The common side 13 has a certain width (specifically, the width along the circumference of the RF coil). The tuning capacitors 40 on the common side 13 further reduce (remove) the coupling between two adjacent coil units (LOOP). Compared to the existing method of overlapping decoupling between two adjacent coils, which requires increasing the area of ​​the coil unit (LOOP), the tuning capacitors 40 on the common side 13 in this embodiment do not require increasing the area of ​​the coil unit (LOOP), saving materials and improving the uniformity of the RF coil. Furthermore, the decoupling method using tuning capacitors 40 coupled on the common side 13 does not require the addition of other decoupling structures (such as decoupling circuits or external decoupling devices).

[0052] Preferably, at least one of the coupling capacitors 40 coupled to the common edge 13 is an adjustable capacitor, meaning its capacitance value can be adjusted. With this configuration, the operator can easily adjust the capacitance value of the corresponding coupling capacitor 40, changing the total capacitance value of the coupling capacitors 40 in the corresponding coil unit LOOP, thereby further improving the coupling degree between adjacent coil unit LOOPs. Regarding the adjustment of the adjustable capacitor's capacitance value, it can be done mechanically. Specifically, the adjustable capacitor has a rotatable adjusting component. The operator can connect to this adjusting component using a suitable tool and drive it to rotate. The rotation of the adjusting component changes the relative distance or relative area of ​​the metal sheets inside the adjustable capacitor, thereby changing the capacitance value. Preferably, the adjustable capacitors on the coil unit LOOP are located on the same side along a preset axis A, for example... Figure 2 The coupling capacitors 40 on the top of all common sides 13 are adjustable capacitors, or the coupling capacitors 40 on the bottom of all common sides 13 are adjustable capacitors. This allows the operator to easily adjust the capacitors on the same side, improving efficiency.

[0053] The inventors discovered that if only one tuning capacitor 40 is placed on the common side 13, it requires a large capacitor with high voltage rating, which is inconvenient for the structural design of the RF coil. Furthermore, the decoupling effect on the adjacent coil unit (LOOP) is not ideal. However, by using at least two tuning capacitors 40, smaller capacitor values ​​can be used, the capacitor size is dispersed, and the capacitor distribution is more uniform, thus improving the decoupling effect on the adjacent coil unit (LOOP).

[0054] It should be noted that the first leg 11, the second leg 12, and the common side 13 mentioned above in relation to the coil unit LOOP of this embodiment can be made of conductive materials such as copper foil. The first leg 11, the second leg 12, and the common side 13 can be integrally formed or separately formed and then connected sequentially. Optionally, the copper foil has a set width, and one or more slots are provided on the copper foil that are parallel to or extend circumferentially along a preset axis A. By providing such slots, the eddy current effect on the coil unit LOOP can be reduced.

[0055] As is generally known, the radio frequency (RF) coil is a key component of MRI equipment. The RF coil can have a transmitting function, or simultaneously have both transmitting and receiving functions. In this embodiment, the RF coil has both transmitting and receiving functions. Specifically, when the RF coil is in transmitting mode, it emits RF pulses to the subject to generate a radio frequency field, causing some atoms containing an odd number of protons (such as hydrogen atoms) within the subject's body to absorb energy and resonate. When the RF coil is in receiving mode, it receives the MR signal (similar to a radio wave) generated by the atomic resonance within the subject's body. The RF coil in this embodiment can further be a body emitter coil.

[0056] When the RF coil has both transmitting and receiving functions, this embodiment can adjust the state of the RF coil by configuring a coil switching module connected to the RF coil. For details, please refer to [link to relevant documentation]. Figure 4 , Figure 4 This is a schematic diagram of a coil adjustment module according to an embodiment of the present invention. Taking an RF coil with 8 coil units (LOOPs) as an example, the power supply port 30 of each coil unit (LOOP) is connected to the coil switching module through a corresponding power line. The switching module has a switching device (T / R Switch) that corresponds one-to-one with the number of power supply ports 30, that is, each switching device acts on one coil unit (LOOP). Figure 4 The example demonstrates numbers 1 through 8, each corresponding to a coil unit LOOP (feed port 30). Specifically, the switching device can be a single-pole double-throw switch. When the feed port 30 is connected to the RF power amplifier (RFPA) via the switch, the RF coil is in the transmitting state; when the feed port 30 is connected to the receiving channel (RX) via the switch, the RF coil is in the receiving state. It should be noted that... Figure 4 The diagram only schematically illustrates the connection relationship between the power supply port 30 corresponding to number 1 and the switching device, as well as the connection relationship between the power amplifier (RFPA1) and the receiving channel (RX1). The connections between the power supply port 30 and the switching device corresponding to other numbers can be derived from this diagram, and will not be described in detail in this embodiment.

[0057] Based on the aforementioned radio frequency coil, this embodiment also provides a magnetic resonance imaging (MRI) device, which includes the radio frequency coil described above. It should be noted that the MRI device described here can be an MR device or a PET-MR device, and this invention is not limited thereto. Since the MRI device includes the radio frequency coil described above, it possesses the beneficial effects brought about by the radio frequency coil. This embodiment will not elaborate on the working principle and other structural components of the MRI device; those skilled in the art can learn about them based on existing technology.

[0058] For example, in an exemplary embodiment, the magnetic resonance imaging device includes a control system, a scanning tube, and the radio frequency coil surrounding the scanning tube. The control system may include an FPGA (Field-Programmable Gate Array) control unit, a digital-to-analog converter (DAC), a radio frequency amplifier, and a power divider connected in sequence. The radio frequency sequence transmitted by the FPGA control unit is sequentially converted into an analog signal by the DAC, amplified by the radio frequency amplifier, and then converted into a drive signal by the power divider and sent to multiple feed ports 30 of the radio frequency coil, thereby driving the radio frequency coil to generate a circularly polarized field.

[0059] In summary, the radio frequency coil and magnetic resonance imaging device provided by this invention include a plurality of ring-shaped coil units, which are circumferentially distributed around a preset axis and connected sequentially; a plurality of feed ports corresponding one-to-one with each coil unit, the feed ports being disposed on the corresponding coil unit; and a plurality of capacitors, with at least one capacitor coupled to each coil unit. With the above configuration, the circuit characteristics of the coil units can be adjusted by setting capacitors. Compared to the prior art, by setting multiple coil units and corresponding multiple feed ports, the number of channels of the radio frequency coil can be increased to more than four, enabling the radio frequency coil to be applied in high-field or ultra-high-field transmission coils. Furthermore, the cooperation of multiple coil units and multiple feed ports can also improve the field uniformity of the radio frequency coil.

[0060] The above description is only a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the present invention.

Claims

1. A radio frequency coil, used in a magnetic resonance imaging device, characterized in that, include: Multiple loop-shaped coil units (LOOPs) are circumferentially distributed around a predetermined axis (A) and connected sequentially. Multiple power supply ports (30) are provided on the corresponding coil unit (LOOP) and each of the coil units (LOOP) is provided with one power supply port (30). Multiple capacitors (20, 40), with at least one of the capacitors (20, 40) coupled to each of the coil units (LOOP). The capacitors (20, 40) include frequency modulation capacitors (20), the sum of the capacitance values ​​of all the frequency modulation capacitors (20) on each coil unit (LOOP) is the frequency modulation capacitance value, and the frequency modulation capacitance values ​​of at least two coil units (LOOP) are not equal.

2. The radio frequency coil according to claim 1, characterized in that, At least one of the capacitors (20, 40) on each of the coil units (LOOP) is an adjustable capacitor.

3. The radio frequency coil according to claim 1, characterized in that, Multiple capacitors (20, 40) are coupled to each of the coil units (LOOP), at least a first portion of the capacitors (20, 40) being frequency modulation capacitors (20) and at least a second portion of the capacitors (20, 40) being tuning coupling capacitors (40).

4. The radio frequency coil according to claim 3, characterized in that, The coil unit (LOOP) has a first leg (11) and a second leg (12) arranged opposite to each other along the preset axis (A), and at least one of the frequency modulation capacitors (20) are coupled to the first leg (11) and the second leg (12), respectively.

5. The radio frequency coil according to claim 1, characterized in that, The coil unit (LOOP) has a first leg (11) and a second leg (12) arranged opposite to each other along the direction of the preset axis (A); the power supply port (30) is disposed on the first leg (11) or the second leg (12) of the corresponding coil unit (LOOP).

6. The radio frequency coil according to claim 5, characterized in that, All the feed ports (30) corresponding to the coil units (LOOP) are located on the same side along the direction of the preset axis (A).

7. The radio frequency coil according to claim 4 or 5, characterized in that, The first leg (11) of all the coil units (LOOP) is located on one side of the direction of the preset axis (A), and the second leg (12) of all the coil units (LOOP) is located on the other side of the direction of the preset axis (A); wherein, the first leg (11) of all the coil units (LOOP) are sequentially connected along the circumference of the radio frequency coil to form a first closed loop (110), and / or, the second leg (12) of all the coil units (LOOP) are sequentially connected along the circumference of the radio frequency coil to form a second closed loop (120).

8. The radio frequency coil according to claim 3, characterized in that, Two adjacent coil units (LOOP) share a common side to form a common side. Multiple common sides (13) of the radio frequency coil are circumferentially distributed around the preset axis (A). At least two tuning capacitors (40) are coupled on each common side (13) of the radio frequency coil.

9. A magnetic resonance imaging device, characterized in that, Includes the radio frequency coil according to any one of claims 1 to 6 or claim 8.

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