A dual-channel radio frequency coil and its design method

Abstract

The present application discloses a dual-channel radio frequency coil and a design method thereof, relating to the field of magnetic resonance imaging technology. The dual-channel radio frequency coil includes a solenoid coil and a saddle coil located outside the solenoid coil; the solenoid coil includes a spiral ring coil winding and a wire component; the spiral ring coil winding includes a plurality of turns of spiral ring coil; the saddle coil includes a first saddle coil group, a second saddle coil group and a matching circuit; the matching circuit includes a tuning component, a first coil assembly, a first tuning network capacitor, a first balun, a matching excitation element, a second balun, a second tuning network capacitor and a second coil assembly connected in sequence; the first coil assembly is connected to the first saddle coil group. The present application can improve signal receiving capability and imaging uniformity.

Description

Technical Field

[0001] The present application relates to the field of magnetic resonance imaging technology, and in particular to a dual-channel radio frequency coil and a design method thereof. Background Art

[0002] Currently, magnetic resonance imaging (MRI) technology has been widely used in the field of medical imaging. Traditional high-field and medium-field MRI systems can achieve high image resolution and signal-to-noise ratio. However, in certain specific application scenarios, such as portable imaging devices, resource-constrained environments, and situations where patient safety is more demanding (such as avoiding the heating effect caused by high field strength), ultra-low field magnetic resonance imaging (ULF-MRI) has become an important alternative. Ultra-low field MRI has the advantages of low field strength and high safety, but it also faces some key challenges: weak signal strength: Due to the low magnetic field strength of ultra-low fields, the magnetic resonance signal generated is very weak, making it difficult to obtain sufficient signal strength, resulting in poor image quality; high noise interference: In ultra-low field environments, the signal-to-noise ratio is usually low, and the receiving coil is easily affected by external electromagnetic interference and system noise, which reduces the imaging effect; matching and tuning difficulties: Traditional single-channel RF coils are difficult to achieve precise matching and tuning under low field strength conditions, resulting in low signal transmission efficiency and unsatisfactory imaging results.

[0003] Existing single-channel or traditional coil designs have weak signal reception capabilities and imaging uniformity in low-field strength environments. Summary of the Invention

[0004] The purpose of this application is to provide a dual-channel radio frequency coil and a design method thereof, which can effectively improve signal reception capability and imaging uniformity in a low field strength environment.

[0005] To achieve the above objectives, this application provides the following solutions:

[0006] In a first aspect, the present application provides a dual-channel radio frequency coil, comprising a solenoid coil and a saddle coil located outside the solenoid coil.

[0007] The solenoid coil includes a spiral ring coil winding and a wire component; the spiral ring coil winding includes several turns of spiral ring coil connected in sequence; the wire component is composed of an upper horizontal wire, a lower horizontal wire, a solenoid vertical wire, an upper capacitor element of the solenoid coil and a lower excitation element in the middle of the solenoid coil; one end of the upper horizontal wire is connected to one end of the upper capacitor element of the solenoid coil, and the other end of the upper horizontal wire is connected to the solenoid vertical wire; the other end of the upper capacitor element of the solenoid coil is connected to the first turn of the spiral ring coil; the end of the lower horizontal wire is connected to one end of the lower excitation element in the solenoid coil, and the other end of the lower horizontal wire is connected to the solenoid vertical wire; the other end of the lower excitation element in the solenoid coil is connected to the last turn of the spiral ring coil; the upper capacitor element of the solenoid coil is used to adjust the resonant frequency of the solenoid coil;

[0008] The saddle coil comprises a first saddle coil group, a second saddle coil group and a matching circuit; the first saddle coil group and the second saddle coil group are arranged in a mirror image;

[0009] The matching circuit includes a tuning component, a first coil assembly, a first tuning network capacitor, a first balun, a matching excitation element, a second balun, a second tuning network capacitor and a second coil assembly connected in sequence; the first coil assembly is connected to the first saddle coil group; the tuning component includes a tuning capacitor and a matching inductor; the tuning component, the first tuning network capacitor and the second tuning network capacitor are used to adjust the resonant frequency of the saddle coil.

[0010] Optionally, the helical toroidal coil winding includes a first helical toroidal coil group, a second helical toroidal coil group, a third helical toroidal coil group, a fourth helical toroidal coil group and a fifth helical toroidal coil group; the first helical toroidal coil group includes 3 turns of the first helical toroidal coil; the second helical toroidal coil group includes 2 turns of the second helical toroidal coil; the third helical toroidal coil group includes 18 turns of the third helical toroidal coil; the fourth helical toroidal coil group includes 2 turns of the fourth helical toroidal coil; the fifth helical toroidal coil group includes 2 turns of the fifth helical toroidal coil.

[0011] Optionally, the turn distances between the first spiral toroidal coils, the turn distances between the second spiral toroidal coils, the turn distances between the third spiral toroidal coils, the turn distances between the fourth spiral toroidal coils, and the turn distances between the fifth spiral toroidal coils are 1 cm or 0.5 cm.

[0012] Optionally, first radii of the first helical loop coil, the second helical loop coil, the third helical loop coil, the fourth helical loop coil, and the fifth helical loop coil are equal.

[0013] Optionally, the first radius is 0.12 m.

[0014] Optionally, the first saddle-shaped coil group includes an upper left semicircular coil, a lower left semicircular coil, a left front vertical wire, and a left rear vertical wire; two endpoints of the upper left semicircular coil are respectively connected to one end of the left front vertical wire and one end of the left rear vertical wire; two endpoints of the lower left semicircular coil are respectively connected to the other end of the left front vertical wire and the other end of the left rear vertical wire;

[0015] The second saddle-shaped coil group includes an upper right semicircular coil, a lower right semicircular coil, a right front vertical wire, and a right rear vertical wire; two endpoints of the upper right semicircular coil are respectively connected to one end of the right front vertical wire and one end of the right rear vertical wire; two endpoints of the lower right semicircular coil are respectively connected to the other end of the right front vertical wire and the other end of the right rear vertical wire;

[0016] The upper left semicircular coil and the lower left semicircular coil are arranged in parallel with the upper right semicircular coil and the lower right semicircular coil.

[0017] Optionally, the second radii of the first and second circular rings are equal; the first circular ring is composed of an upper left semicircular ring coil and a lower left semicircular ring coil; the second circular ring is composed of an upper right semicircular ring coil and a lower right semicircular ring coil.

[0018] Optionally, the second radius is 0.13 m.

[0019] Optionally, the height of the saddle-shaped coil is 0.24 m.

[0020] In a second aspect, the present application provides a design method for a dual-channel radio frequency coil, comprising:

[0021] The genetic algorithm is used to optimize the geometric parameters of the solenoid to obtain the optimal geometric parameters of the solenoid; the geometric parameters of the solenoid include the radius of the spiral ring coil, the turn distance between the spiral ring coils and the number of windings of the spiral ring coil winding; the number of windings of the spiral ring coil winding is the number of spiral ring coils;

[0022] The dual-channel radio frequency coil according to the first aspect is prepared based on the optimal solenoid geometric parameters.

[0023] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0024] The main problems with existing single-channel or traditional coils include: 1) Poor reception uniformity: The magnetic field distribution of a single-channel coil is uneven, resulting in large variations in signal strength in the image, affecting diagnostic effectiveness. 2) Inaccurate matching: Due to poor matching between the coil and the system, energy transmission efficiency is low, causing severe signal attenuation. 3) Inadequate noise suppression: Existing coil designs are sensitive to environmental noise and cannot effectively isolate and suppress external interference.

[0025] Based on the above problems, the present application provides a dual-channel radio frequency coil and its design method, which realizes circular polarization field distribution through a saddle-shaped coil, so that the magnetic field is evenly covered in the horizontal and vertical directions, significantly improving the signal reception uniformity and sensitivity, and effectively reducing the dead zone and uneven area in signal reception, which is particularly suitable for ultra-low field magnetic resonance imaging (ULF-MRI) environment; by precisely adjusting the tuning capacitor and matching inductor, the dual-channel radio frequency coil can accurately resonate at the Larmor frequency, and the adjusted matching circuit ensures the optimal impedance matching of the coil, minimizes signal reflection and energy loss, thereby improving the overall signal transmission efficiency and imaging quality. The synergistic effect of the above-mentioned devices improves the imaging capability of the system under low field strength. The circular polarization design and matching circuit adjustment enable the dual-channel coil to effectively adapt to low-field magnetic resonance imaging, providing clearer and higher-resolution images than traditional single-channel coils. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 A schematic diagram of the overall structure of a dual-channel radio frequency coil provided in one embodiment of the present application;

[0028] Figure 2 A schematic structural diagram of a solenoid coil provided in one embodiment of the present application;

[0029] Figure 3 A schematic structural diagram of a saddle coil provided in one embodiment of the present application;

[0030] Figure 4 A schematic diagram of a matching circuit provided in an embodiment of the present application.

[0031] Reference numerals:

[0032] Saddle coil 1, solenoid coil 2, first spiral ring coil group 3, second spiral ring coil group 4, third spiral ring coil group 5, fourth spiral ring coil group 6, fifth spiral ring coil group 7, matching circuit 8, upper horizontal wire 9, lower horizontal wire 10, solenoid vertical wire 11, upper capacitor element of the solenoid coil 12, lower middle excitation element of the solenoid coil 13, upper left half ring coil 1 4, upper right semicircular coil - 15, matching excitation element - 16, lower left semicircular coil - 17, lower right semicircular coil - 18, left front vertical wire - 19, right front vertical wire - 20, left rear vertical wire - 21, right rear vertical wire - 22, first coil assembly - 23, second coil assembly - 24, first balun - 25, second balun - 26, first tuning network capacitor - 27, tuning component - 28, second tuning network capacitor - 29. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0034] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0035] In an exemplary embodiment, Figure 1 As shown, a dual-channel radio frequency coil is provided, comprising a solenoid coil 2 and a saddle coil 1 located outside the solenoid coil 2 .

[0036] like Figure 2As shown, the solenoid coil 2 includes a spiral ring coil winding and a wire component; the spiral ring coil winding includes several turns of spiral ring coils connected in sequence; the wire component is composed of an upper horizontal wire 9, a lower horizontal wire 10, a solenoid vertical wire 11, an upper capacitor element 12 of the solenoid coil and a lower excitation element 13 in the middle of the solenoid coil; one end of the upper horizontal wire 9 is connected to one end of the upper capacitor element 12 of the solenoid coil, and the other end of the upper horizontal wire 9 is connected to the solenoid vertical wire 11; the other end of the upper capacitor element 12 of the solenoid coil is connected to the first turn of the spiral ring coil; the end of the lower horizontal wire 10 is connected to one end of the lower excitation element 13 in the solenoid coil, and the other end of the lower horizontal wire 10 is connected to the solenoid vertical wire 11; the other end of the lower excitation element 13 in the solenoid coil is connected to the last turn of the spiral ring coil; the upper capacitor element 12 of the solenoid coil is used to adjust the resonant frequency of the solenoid coil 2.

[0037] The lower excitation element 13 in the solenoid coil is an excitation current source device, and S-parameter discrete edge ports can be used during simulation.

[0038] The spiral coil windings include a first spiral coil group 3, a second spiral coil group 4, a third spiral coil group 5, a fourth spiral coil group 6, and a fifth spiral coil group 7. These groups are connected sequentially from top to bottom. The first spiral coil group 3 includes three turns of the first spiral coil; the second spiral coil group 4 includes two turns of the second spiral coil; the third spiral coil group 5 includes 18 turns of the third spiral coil; the fourth spiral coil group 6 includes two turns of the fourth spiral coil; and the fifth spiral coil group 7 includes two turns of the fifth spiral coil.

[0039] The first helical ring coil group 3 and the fifth helical ring coil group 7 are respectively connected to the upper capacitor element 12 of the helical coil and the lower excitation element 13 in the middle of the helical coil. The outsides of the upper capacitor element 12 of the helical coil and the lower excitation element 13 in the middle of the helical coil are respectively connected to one end of the upper horizontal wire 9 and one end of the lower horizontal wire 10.

[0040] The turns between the first spiral toroidal coils, the turns between the second spiral toroidal coils, the turns between the third spiral toroidal coils, the turns between the fourth spiral toroidal coils, and the turns between the fifth spiral toroidal coils are 1 cm or 0.5 cm. In a specific embodiment, the turns between the first spiral toroidal coils may be 1 cm, the turns between the second spiral toroidal coils may be 0.5 cm, the turns between the third spiral toroidal coils may be 1 cm, the turns between the fourth spiral toroidal coils may be 0.5 cm, and the turns between the fifth spiral toroidal coils may be 1 cm.

[0041] The first radii of the first spiral loop coil, the second spiral loop coil, the third spiral loop coil, the fourth spiral loop coil and the fifth spiral loop coil are equal. Preferably, the first radius is 0.12 m.

[0042] like Figure 3 As shown, the saddle coil 1 includes a first saddle coil group 1, a second saddle coil group 1 and a matching circuit 8; the first saddle coil group 1 and the second saddle coil group 1 are arranged in a mirror image.

[0043] The first saddle coil group 1 includes an upper left semicircular coil 14, a lower left semicircular coil 17, a left front vertical wire 19 and a left rear vertical wire 21; the two endpoints of the upper left semicircular coil 14 are respectively connected to one end of the left front vertical wire 19 and one end of the left rear vertical wire 21; the two endpoints of the lower left semicircular coil 17 are respectively connected to the other end of the left front vertical wire 19 and the other end of the left rear vertical wire 21.

[0044] The second saddle coil group 1 includes an upper right semicircular coil 15, a lower right semicircular coil 18, a right front vertical wire 20, and a right rear vertical wire 22. The two endpoints of the upper right semicircular coil 15 are connected to one end of the right front vertical wire 20 and one end of the right rear vertical wire 22, respectively. The two endpoints of the lower right semicircular coil 18 are connected to the other ends of the right front vertical wire 20 and the other end of the right rear vertical wire 22, respectively. The upper left semicircular coil 14 and the lower left semicircular coil 17 are arranged parallel to the upper right semicircular coil 15 and the lower right semicircular coil 18.

[0045] The first and second rings have the same second radius; the first ring is composed of an upper left semicircular coil 14 and a lower left semicircular coil 17; the second ring is composed of an upper right semicircular coil 15 and a lower right semicircular coil 18. Preferably, the second radius is 0.13m, and the height of the saddle coil 1 is 0.24m.

[0046] like Figure 4As shown, the matching circuit 8 includes a tuning component 28, a first coil component 23, a first tuning network capacitor 27, a first balun 25, a matching excitation element 16, a second balun 26, a second tuning network capacitor 29 and a second coil component 24 connected in sequence; the first coil component 23 is connected to the first saddle coil 1 group; the tuning component 28 includes a tuning capacitor Ct and a matching inductor Lm; the tuning component 28, the first tuning network capacitor 27 and the second tuning network capacitor 29 are used to adjust the resonant frequency of the saddle coil 1.

[0047] It should be noted that the matching excitation element 16 is an excitation current source device, and S-parameter discrete edge ports can be used during simulation.

[0048] The lower end of the left front vertical wire 19 is connected to the first coil assembly 23, the first tuning network capacitor 27, the first balun 25, the matching excitation element 16, the second balun 26, the second tuning network capacitor 29 and the second coil assembly 24 in sequence to achieve precise tuning and impedance matching of the dual-channel RF coil, ensuring the optimal working state of the system at the target Larmor frequency.

[0049] In an exemplary embodiment, the present application provides a dual-channel radio frequency coil design method, characterized in that the dual-channel radio frequency coil design method includes the following steps 1 to 3:

[0050] Step 1: Using a genetic algorithm, optimize the solenoid geometric parameters to obtain optimal solenoid geometric parameters. The solenoid geometric parameters include the radius of the helical toroidal coil, the turn spacing between the helical toroidal coils, and the number of windings of the helical toroidal coil windings. The number of windings of the helical toroidal coil windings refers to the number of helical toroidal coils. The dual-channel RF coil described above is manufactured based on the optimal solenoid geometric parameters. The turn spacing between the helical toroidal coils refers to the distance between adjacent helical toroidal coil groups.

[0051] The solenoid geometry was optimized using PyCharm. Based on objective functions (e.g., maximizing signal strength and improving uniformity), the solenoid geometry was optimized. This step utilized a genetic algorithm (GA) to automatically adjust the solenoid radius, coil spacing, and number of windings to achieve the optimal magnetic field distribution.

[0052] The fitness of the genetic algorithm is the objective function mentioned above. The individuals in the population are the radius, coil spacing, and number of windings of the solenoid. The Biot-Savart theorem is used to calculate the magnetic field strength B1 based on the radius, number of coil turns, and number of windings of the solenoid, thereby calculating the signal strength and uniformity. The objective function and the main parameters involved are as follows:

[0053] Main parameters:

[0054] Radius r: The radius of the helical toroidal coil, which affects the concentration of the magnetic field.

[0055] Coil spacing d: The distance between adjacent spiral ring coil groups, which affects the uniformity of the coil.

[0056] Number of windings n: The total number of turns of the coil, that is, the number of windings of the spiral toroidal coil winding, affects the magnetic field strength.

[0057] Known quantities: initial geometric parameter settings, optimization objectives.

[0058] Unknown quantity: optimal geometric parameter configuration.

[0059] Fitness: Minimize the fitness value to solve the optimal solenoid geometric parameters.

[0060] The objective function is calculated as follows:

[0061] fitness=ξ sim -ppm

[0062]

[0063] Where, fitness is the fitness; ξ sim is the signal strength, which is used to describe the simulation results of a certain signal; ppm is the uniformity (parts per million), which is used to measure the change of the maximum and minimum values ​​of the magnetic field strength relative to the average value, and is usually used to express non-uniformity or error; ω0 is the resonant frequency, which is related to the signal resonant frequency; Z0 is the characteristic impedance, which is related to the electromagnetic wave propagation characteristics; Q is the quality factor, which is used to measure the energy loss of the system; L is the inductance, which is the inductance and is related to the radius and number of turns of the spiral ring coil; B 1x is the component of the magnetic field intensity in the x-axis direction obtained by Biot-Savart; M xy is the transverse component of the magnetization vector in the xy plane, i represents the current, j represents the imaginary unit, ν represents the unit volume, and B max is the maximum magnetic field strength, B min is the minimum value of magnetic field strength, B mean is the average magnetic field strength.

[0064] Step 2: Using electromagnetic simulation software CST, engineers designed the radius R and height H of saddle coil 1, as well as the shape and path of the wire in saddle coil 1, to achieve circular polarization.

[0065] The saddle coil is designed to achieve circular polarization, improving imaging signal uniformity and sensitivity. The saddle coil's geometry enables it to generate magnetic fields in both the horizontal and vertical directions, resulting in a circularly polarized field distribution. This design effectively enhances signal reception, especially under low-field conditions.

[0066] Main parameters:

[0067] The radius R and height H of the saddle coil 1 determine the coverage of the magnetic field.

[0068] Wire shape and routing: Ensure symmetrical current distribution for ideal polarization.

[0069] Known quantities: Basic design shape and size requirements of the coil.

[0070] Unknown quantities: specific geometric parameters to achieve optimal circular polarization.

[0071] Step 3: Circuit engineers use the circuit simulation software CST Design Studio to adjust the matching circuit 8 and optimize the design so that the coil operates at the Larmor frequency and optimizes performance.

[0072] Adjust the matching circuit 8 of the dual-channel RF coils so that each coil operates at the target Larmor frequency, ensuring optimal signal transmission and reception. By optimizing the parameters of the tuning capacitors and matching inductors, precise coil resonance and impedance matching are achieved, improving signal strength and signal-to-noise ratio.

[0073] Main parameters:

[0074] Tuning capacitor Ct: Used to fine-tune the resonant frequency of the coil to the Larmor frequency, ensuring that the coil operates efficiently at the target frequency.

[0075] Matching inductor Lm: Adjust the inductance value to achieve impedance matching, reduce signal reflection, and improve signal coupling efficiency.

[0076] Frequency adjustment range: The tuning capacitor and matching inductor in matching circuit 8 are designed to accurately cover the required Larmor frequency (3.02 MHz at 70.9 mT).

[0077] Known Quantity: The design target frequency of the coil is the Larmor frequency.

[0078] Unknowns: Optimal matching circuit 8 parameter configuration, including the exact values ​​of the tuning capacitor and matching inductor.

[0079] The geometric parameters of the solenoid are optimized based on genetic algorithms and combined with a specific saddle-shaped structure to achieve optimal magnetic field distribution and signal reception efficiency, significantly improving the uniformity and sensitivity of imaging.

[0080] After the above steps, the design parameters of the solenoid coil 2 are as follows: the first radius r is 0.12m, and the coil spacing d is distributed in two distributions, 0.01m and 0.005m, which can effectively improve the uniformity of the coil's magnetic field; the total number of coil windings n is 27, which helps to enhance the magnetic field strength. Specifically, the helical coil windings, from top to bottom, include a helical coil with 3 turns and a turn spacing of 1cm, a helical coil with 2 turns and a turn spacing of 0.5cm, a helical coil with 18 turns and a turn spacing of 1cm, a helical coil with 2 turns and a turn spacing of 0.5cm, and a helical coil with 2 turns and a turn spacing of 1cm.

[0081] The dimensions of the saddle-shaped coil 1 are as follows: the second radius R is 0.13 m and the height H is 0.24 m. Such a structure can maximize the coverage of the magnetic field.

[0082] The capacitance parameters of matching circuit 8 are set as follows: 100pF for the upper solenoid coil capacitor 12, used for tuning solenoid coil 2; 220pF for the first tuning network capacitor 27, and 150pF for the second tuning network capacitor 29, used for signal balance-unbalance conversion, impedance matching, and noise suppression, ensuring efficient and stable signal transmission from the RF coil; and 180pF for the tuning network of saddle coil 1. Based on the above, the coordinated optimization of solenoid coil 2 and saddle coil 1 enables them to operate at the same Larmor frequency of 3.02MHz, thereby improving signal transmission efficiency and imaging quality.

[0083] Compared with the existing technology, the dual-channel RF coil design method of this application has the following significant advantages:

[0084] 1. Improve signal reception uniformity and sensitivity

[0085] 2. Optimize matching performance and achieve precise resonance by adjusting matching circuit 8

[0086] 3. Reduce noise and improve signal-to-noise ratio: The optimized solenoid geometry and the circularly polarized saddle coil design work together to effectively suppress background noise interference. The genetic algorithm-optimized solenoid geometry results in a more concentrated and stable magnetic field, while the circular polarization design further homogenizes signal reception, significantly improving the signal-to-noise ratio.

[0087] 4. Enhanced Imaging and Adaptability to Low-Field-Strength Conditions: The aforementioned steps work together to enhance the system's imaging capabilities at low field strengths. The circular polarization design and matching circuit adjustments enable the dual-channel coil to effectively adapt to low-field MRI, providing clearer, higher-resolution images than traditional single-channel coils.

[0088] Circular polarization effect: The saddle coil design enables the magnetic field to act on the sample in multiple directions simultaneously, enhancing signal uniformity.

[0089] Matching circuit 8 optimization: Fine adjustment of matching circuit 8 ensures efficient energy transmission and minimal reflection, reducing energy loss.

[0090] Improved signal-to-noise ratio: The optimized coil and circuit design result in stronger received signals and lower noise, ultimately enhancing the accuracy and effectiveness of imaging.

[0091] Based on the above, the performance of the dual-channel RF coil provided in this application in ultra-low field magnetic resonance imaging applications has been significantly improved, providing reliable technical support for the acquisition of high-quality images and opening up new avenues for the widespread application of magnetic resonance technology.

[0092] Description: Utilizes a conventional solenoid coil2 and optimizes signal reception by reducing external noise interference through improved shielding materials and design.

[0093] Advantages and disadvantages: This solution has improved shielding effect and noise suppression, but the magnetic field uniformity and circular polarization effect of the solenoid are still not as good as those of the saddle coil, and the overall imaging effect is not ideal.

[0094] Compared to existing solutions, the dual-channel RF coil design in this application combines the circular polarization advantages of a saddle coil with an optimized matching circuit design, providing improved signal uniformity, noise suppression, and matching. Therefore, the solution in this application has unique advantages and wider applicability in ultra-low-field magnetic resonance imaging applications.

[0095] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0096] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A dual-channel radio frequency coil, characterized in that: The dual-channel radio frequency coil includes a solenoid coil and a saddle coil located outside the solenoid coil; The solenoid coil includes a spiral ring coil winding and a wire component; the spiral ring coil winding includes several turns of spiral ring coil connected in sequence; the wire component is composed of an upper horizontal wire, a lower horizontal wire, a solenoid vertical wire, an upper capacitor element of the solenoid coil and a lower excitation element in the middle of the solenoid coil; one end of the upper horizontal wire is connected to one end of the upper capacitor element of the solenoid coil, and the other end of the upper horizontal wire is connected to the solenoid vertical wire; the other end of the upper capacitor element of the solenoid coil is connected to the first turn of the spiral ring coil; the end of the lower horizontal wire is connected to one end of the lower excitation element in the solenoid coil, and the other end of the lower horizontal wire is connected to the solenoid vertical wire; the other end of the lower excitation element in the solenoid coil is connected to the last turn of the spiral ring coil; the upper capacitor element of the solenoid coil is used to adjust the resonant frequency of the solenoid coil; The saddle coil comprises a first saddle coil group, a second saddle coil group and a matching circuit; the first saddle coil group and the second saddle coil group are arranged in a mirror image; The matching circuit includes a tuning component, a first coil assembly, a first tuning network capacitor, a first balun, a matching excitation element, a second balun, a second tuning network capacitor and a second coil assembly connected in sequence; the first coil assembly is connected to the first saddle coil group; the tuning component includes a tuning capacitor and a matching inductor; the tuning component, the first tuning network capacitor and the second tuning network capacitor are used to adjust the resonant frequency of the saddle coil.

2. The dual-channel radio frequency coil according to claim 1, characterized in that The spiral toroidal coil winding includes a first spiral toroidal coil group, a second spiral toroidal coil group, a third spiral toroidal coil group, a fourth spiral toroidal coil group and a fifth spiral toroidal coil group; the first spiral toroidal coil group includes 3 turns of the first spiral toroidal coil; the second spiral toroidal coil group includes 2 turns of the second spiral toroidal coil; the third spiral toroidal coil group includes 18 turns of the third spiral toroidal coil; the fourth spiral toroidal coil group includes 2 turns of the fourth spiral toroidal coil; the fifth spiral toroidal coil group includes 2 turns of the fifth spiral toroidal coil.

3. The dual-channel radio frequency coil according to claim 2, characterized in that: The turn distances between the first spiral toroidal coils, the turn distances between the second spiral toroidal coils, the turn distances between the third spiral toroidal coils, the turn distances between the fourth spiral toroidal coils, and the turn distances between the fifth spiral toroidal coils are 1 cm or 0.5 cm.

4. The dual-channel radio frequency coil according to claim 2, wherein: The first radii of the first helical toroidal coil, the second helical toroidal coil, the third helical toroidal coil, the fourth helical toroidal coil, and the fifth helical toroidal coil are equal.

5. The dual-channel radio frequency coil according to claim 4, characterized in that: The first radius is 0.12 m.

6. The dual-channel radio frequency coil according to claim 1, characterized in that: The first saddle-shaped coil group includes an upper left semicircular coil, a lower left semicircular coil, a left front vertical wire, and a left rear vertical wire; two endpoints of the upper left semicircular coil are respectively connected to one end of the left front vertical wire and one end of the left rear vertical wire; two endpoints of the lower left semicircular coil are respectively connected to the other end of the left front vertical wire and the other end of the left rear vertical wire; The second saddle-shaped coil group includes an upper right semicircular coil, a lower right semicircular coil, a right front vertical wire, and a right rear vertical wire; two endpoints of the upper right semicircular coil are respectively connected to one end of the right front vertical wire and one end of the right rear vertical wire; two endpoints of the lower right semicircular coil are respectively connected to the other end of the right front vertical wire and the other end of the right rear vertical wire; The upper left semicircular coil and the lower left semicircular coil are arranged in parallel with the upper right semicircular coil and the lower right semicircular coil.

7. The dual-channel radio frequency coil according to claim 6, characterized in that: The second radii of the first and second circular rings are equal; the first circular ring is composed of an upper left semicircular ring coil and a lower left semicircular ring coil; the second circular ring is composed of an upper right semicircular ring coil and a lower right semicircular ring coil.

8. The dual-channel radio frequency coil according to claim 7, characterized in that: The second radius is 0.13 m.

9. The dual-channel radio frequency coil according to claim 1, characterized in that: The height of the saddle coil is 0.24 m.

10. A design method for a dual-channel radio frequency coil, characterized in that: The design method of the dual-channel radio frequency coil includes: The genetic algorithm is used to optimize the geometric parameters of the solenoid to obtain the optimal geometric parameters of the solenoid; the geometric parameters of the solenoid include the radius of the spiral ring coil, the turn distance between the spiral ring coils and the number of windings of the spiral ring coil winding; the number of windings of the spiral ring coil winding is the number of spiral ring coils; The dual-channel radio frequency coil according to claim 1 is prepared based on the optimal solenoid geometric parameters.

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