Multi-nuclide magnetic resonance excitation coil and manufacturing method

Abstract

The invention discloses a multi-nuclide magnetic resonance excitation coil and also discloses a manufacturing method of the multi-nuclide magnetic resonance excitation coil, and coupled reverse currents are mutually offset by constructing an 8-shaped loop. Compared with a traditional nested birdcage coil, on the basis that the performance of the second birdcage coil on the inner layer in a traditional scheme is guaranteed, the shielding effect between the inner layer and the outer layer is fundamentally eliminated, and the excitation efficiency and sensitivity of the coil on the outer layer are indirectly improved; according to the nested birdcage coil, the second birdcage coil on the inner layer has an inner cavity diameter closer to that of the first birdcage coil on the outer layer; according to the exchange board, single-point or multi-point insertion can be carried out by breaking the cage leg structure, and an 8-shaped loop is added into a coil of a traditional nested structure at the minimum transformation cost.

Description

Technical Field

[0001] The present invention belongs to the field of magnetic resonance imaging technology, and specifically relates to a multi-nuclide magnetic resonance excitation coil and a method for manufacturing the multi-nuclide magnetic resonance excitation coil. The present invention is suitable for situations where high radio frequency field uniformity is required in multi-nuclide nuclear magnetic resonance and multi-nuclide magnetic resonance imaging technologies. Background Art

[0002] Although non 1 The magnetic resonance technology of H nuclei has been used in the spectrum analysis of materials for a long time, but its application in the field of magnetic resonance imaging (MRI) has just started. As an emerging field of magnetic resonance imaging, multi-nuclear MRI (referring to the traditional 1 H nuclear MRI and one or more non 1 H nuclear MRI combined imaging technology) has demonstrated clinical transformation and application potential in tissue metabolism, cancer detection, and lung ventilation assessment. 1 Since the introduction of H-NMR technology, the ability to generate high-quality dual-frequency RF pulses within a single RF coil has been a technical pain point for multi-nuclear magnetic resonance imaging (including multi-nuclear NMR and multi-nuclear MRI). In the MRI field, multi-nuclear magnetic resonance imaging has the following limitations with regard to RF coils:

[0003] Using a separate coil as the X-channel and installing it inside the existing H-channel transmitting coil is a common solution that offers relatively high isolation (known as a nested birdcage coil approach). However, to maintain isolation, this approach requires a certain radial distance between the X-channel coil and the H-channel coil. This further compresses the already limited internal cavity space, resulting in reduced patient comfort and limiting examination capabilities for larger patients. Summary of the Invention

[0004] The purpose of the present invention is to address the above-mentioned problems existing in the prior art and to provide a multi-nuclide magnetic resonance excitation coil and a method for manufacturing the multi-nuclide magnetic resonance excitation coil.

[0005] The above-mentioned purpose of the present invention is achieved by the following technical means:

[0006] A multi-nuclide magnetic resonance excitation coil comprises a nested first birdcage coil and a second birdcage coil, wherein the second birdcage coil is embedded inside the first birdcage coil, and the second birdcage coil comprises a pair of parallel second end rings, each second end ring comprising a plurality of identical second end ring segments, each second end ring segment comprising identical first sub-end ring segments and second sub-end ring segments, wherein the second end ring segment on one second end ring is connected to the corresponding second end ring segment on another second end ring via a second cage leg pair, the second cage leg pair comprising two staggered second cage legs, wherein the first sub-end ring segment of the second end ring segment on one second end ring is connected to the second sub-end ring segment of the second end ring segment on the corresponding position on the other second end ring via a second cage leg, and the second sub-end ring segment of the second end ring segment on one second end ring is connected to the first sub-end ring segment of the second end ring segment on the corresponding position on the other second end ring via a second cage leg.

[0007] As described above, a second distributed capacitor is provided between adjacent second end ring segments, and a third distributed capacitor is provided between the first sub-end ring segment and the second sub-end ring segment of each second end ring segment. The second distributed capacitor and the third distributed capacitor have different capacitance values.

[0008] The device also includes a matching circuit for a second birdcage coil, which includes a second tuning capacitor and a pair of second matching capacitors, wherein a second distributed capacitor on the second birdcage coil serves as a port capacitor, and two ends of the port capacitor of the second birdcage coil connected in parallel with the second tuning capacitor are respectively connected in series with one end of a second matching capacitor, and the other ends of the two second matching capacitors are led out of the port.

[0009] As described above, the first birdcage coil includes a pair of parallel first end rings, and a plurality of first distributed capacitors are arranged on the first end rings at equal intervals along the circumferential direction. Each first distributed capacitor separates the first end ring into a plurality of identical first end ring segments, and each first end ring segment of one first end ring is connected to each first end ring segment at a corresponding position on the other first end ring through a first cage leg along the axial direction.

[0010] It also includes a matching circuit for the first birdcage coil, which includes a first tuning capacitor and a pair of first matching capacitors, wherein a first distributed capacitor on the first birdcage coil serves as a port capacitor, and the two ends of the port capacitor of the first birdcage coil connected in parallel with the first tuning capacitor are respectively connected in series with one end of a first matching capacitor, and the other ends of the two first matching capacitors are led out of the port.

[0011] It also includes a shielding cover that is mounted on the outside of the first birdcage coil. The shielding cover includes multiple identical shielding strips parallel to the axial direction. All shielding strips are evenly spaced along the circumferential direction. There are gaps between adjacent shielding strips. Gap capacitors are set in the gaps between adjacent shielding strips.

[0012] A method for manufacturing a multi-nuclide magnetic resonance excitation coil comprises the following steps:

[0013] Step 1: Build a shielding cover, and stick shielding strips on the inner cylindrical surface of the first support tube along the axial direction. The gap between adjacent copper foil tapes is smaller than the first set gap, and gap capacitance is set in the gap between adjacent shielding strips.

[0014] Step 2: construct a first birdcage coil, which is arranged on the outer cylindrical surface of the second support tube. The first end ring segment and the first cage leg are both adhered to the outer cylindrical surface of the second support tube using copper foil tape, and a first distributed capacitor is welded between each adjacent end ring segment of the two end rings;

[0015] Step 3: Construct a second birdcage coil. The second birdcage coil is arranged on the outer cylindrical surface of the third support tube. The second sub-end ring segments are all attached to the outer cylindrical surface of the third support tube using copper foil tape. Second distributed capacitors are welded between each end ring segment, and third distributed capacitors are welded between the two sub-end ring segments of each end ring segment. An annular exchange plate is arranged in the middle position between the two second end rings. The exchange plate is provided with multiple connection hole groups that penetrate the ring walls of the end faces on both sides. Each connection hole group is evenly distributed along the circumferential direction of the exchange plate. Each connection hole group includes a first connection hole and a second connection hole of the same length. The first connection hole and the second connection hole are respectively provided with a first connection line and a second connection line.

[0016] An annular exchange plate is fixed to the center of the outer cylindrical surface of the third support tube. For each pair of second cage legs, one end of the two copper foil tapes of one second cage leg is respectively connected to the two ends of the first connecting line, and the other end is respectively connected to the second sub-end ring segment corresponding to one end ring and the first sub-end ring segment corresponding to the other end ring; one end of the two copper foil tapes of the other second cage leg is respectively connected to the two ends of the second connecting line, and the other end is respectively connected to the first sub-end ring segment corresponding to one end ring and the second sub-end ring segment corresponding to the other end ring.

[0017] Step 4: Perform impedance matching on the first birdcage coil and the second birdcage coil respectively.

[0018] Step 5. Adjust the circumferential relative positions of the shielding cover, the first birdcage coil, and the second birdcage coil: Fix the shielding cover, the first birdcage coil, and the second birdcage coil, and adjust the circumferential relative positions of the shielding cover, the first birdcage coil, and the second birdcage coil by rotating them one by one, and then lock them with studs.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The present invention cancels out the coupled reverse currents by constructing an "8"-shaped loop. Compared with the traditional nested birdcage coil, the present invention fundamentally eliminates the shielding effect between the inner and outer layers while ensuring the performance of the second birdcage coil in the traditional solution, indirectly improving the excitation efficiency and sensitivity of the outer coil.

[0021] (2) The exchange plate of the present invention can be inserted at a single point or multiple points by breaking the cage leg structure, thereby realizing the operation of adding an "8"-shaped loop to the coil of the traditional nested structure with minimal modification cost;

[0022] (3) The present invention eliminates the shielding effect between the first birdcage coil and the second birdcage coil, allowing the inner second birdcage coil to have an inner diameter closer to that of the outer first birdcage coil. As an MRI transmitting coil, a relatively larger inner diameter is more advantageous. This means that compared with the traditional nested birdcage solution, the MRI scanner using the present invention not only meets the requirements of multi-core MRI but is also compatible with a wider range of patient sizes. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 2 is a schematic structural diagram of a topologically optimized nested first birdcage coil and a second birdcage coil according to the present invention;

[0024] Figure 2 Schematic diagram of the structure of the second birdcage coil of the present invention;

[0025] Figure 3 This is a schematic diagram of an equivalent circuit structure when the second birdcage coil in the inner layer of the present invention works with the first birdcage coil in the outer layer;

[0026] Figure 4 This is a schematic diagram of the equivalent circuit structure of the topologically optimized inner second birdcage coil of the present invention when it is working on its own;

[0027] Figure 5 A schematic diagram of the structure of the connection between the first birdcage coil, the second birdcage coil and the corresponding matching circuits (where A is the matching circuit of the first birdcage coil, and B is the matching circuit of the second birdcage coil);

[0028] Figure 6 Schematic diagram of the enlarged structure of the matching circuit of the first birdcage coil of the present invention;

[0029] Figure 7 Schematic diagram of the enlarged structure of the matching circuit of the second birdcage coil of the present invention;

[0030] Figure 8 It is a structural schematic diagram of the exchange plate used for the modification of an 8-legged birdcage according to the present invention;

[0031] Figure 9The figure shows the comparison of axial RF field strength of a single outer birdcage coil, a traditional nested birdcage coil, and the topologically optimized nested birdcage coil of the present invention (input power 1W).

[0032] Figure 10 This is a schematic diagram of the traditional nested birdcage coil scheme;

[0033] Reference numerals and corresponding component names:

[0034] 1-first birdcage coil; 2-second birdcage coil; 3-first distributed capacitor; 4-second distributed capacitor; 5-third distributed capacitor; 6-first tuning capacitor; 7-second tuning capacitor; 8-first matching capacitor; 9-second matching capacitor; 10-first connecting hole; 11-second connecting hole. DETAILED DESCRIPTION

[0035] In order to facilitate those skilled in the art to understand and implement the present invention, the present invention is further described in detail below with reference to the embodiments. The embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0036] Example 1:

[0037] A multi-nuclide magnetic resonance excitation coil comprises an outer first birdcage coil 1 and an inner second birdcage coil 2, wherein the first birdcage coil 1 and the second birdcage coil 2 are nested, and the second birdcage coil 2 is embedded in the first birdcage coil 1. The second birdcage coil 2 comprises a pair of parallel second end rings, each second end ring comprising a plurality of identical second end ring segments, the number of second end ring segments of the two second end rings being the same, a second distributed capacitor 4 being provided between adjacent second end ring segments, each second end ring segment comprising two identical sub-end ring segments, respectively denoted as a first sub-end ring segment and a second sub-end ring segment, and the first sub-end ring segment and the second sub-end ring segment of each second end ring segment being the same. A third distributed capacitor 5 is provided between the two sub-end ring segments, wherein the second end ring segment on one second end ring is connected to the second end ring segment at a corresponding position on the other second end ring via a second cage leg pair, and the second cage leg pair includes two staggered second cage leg pairs, specifically: the first sub-end ring segment of the second end ring segment on one second end ring is connected to the second sub-end ring segment of the second end ring segment at a corresponding position on the other second end ring via a second cage leg, and the second sub-end ring segment of the second end ring segment on one second end ring is connected to the first sub-end ring segment of the second end ring segment at a corresponding position on the other second end ring via a second cage leg;

[0038] Because the introduced "8"-shaped loop destroys the symmetry of the original birdcage coil structure, the capacitance distributed on the second end ring is equivalently divided into a second distributed capacitance 4 and a third distributed capacitance 5. The capacitance between the end ring segments is used as the second distributed capacitance 4, and the capacitance between the two sub-end ring segments of each end ring segment is used as the third distributed capacitance 5 (also a short-circuit capacitance). To maintain the balanced resonance of the second birdcage coil 2, the capacitance values ​​of the second distributed capacitances 4 and the third distributed capacitances 5 are the same; and to ensure isolation between the "8" shapes, the capacitance values ​​of the second distributed capacitances 4 and the third distributed capacitances 5 are different.

[0039] The second distributed capacitor 4 and the third distributed capacitor 5 are subject to two constraints: at the Larmor frequency of the inner channel, the phase change on both sides of the "8" loop is minimized; at the Larmor frequency of the outer channel, the energy exchange between the "8" loops is minimized. These two indicators can be measured using a vector network analyzer. In actual debugging, the third distributed capacitor 5 can sometimes be replaced by a short circuit, under which condition the phase indicator can be omitted.

[0040] The system also includes a matching circuit for the second birdcage coil 2. The matching circuit for the second birdcage coil 2 includes a second tuning capacitor 7 and a pair of second matching capacitors 9. The two ends of the port capacitor of the second birdcage coil 2 connected in parallel with the second tuning capacitor 7 are respectively connected in series with one end of a second matching capacitor 9. The other ends of the two second matching capacitors 9 are connected to the output port of the X-channel broadband RF power amplifier of the MRI RF system.

[0041] Under the monitoring of the vector network analyzer, the second tuning capacitor 7 and the second matching capacitor 9 are adjusted so that the 110MHz reflection coefficient S 22 (110MHz) <-20dB. Note that in this step, the topology-optimized 8-leg birdcage coil has three different resonance points in the vector network analyzer, and only the first, lowest-frequency resonance point is correct and effective.

[0042] As an implementation method, the first birdcage coil 1 includes a pair of parallel first end rings, and a plurality of first distributed capacitors 3 are arranged on the first end rings at equal intervals along the circumferential direction. Each first distributed capacitor 3 divides the first end ring into a plurality of identical first end ring segments, and each first end ring segment of one first end ring is connected to each first end ring segment at a corresponding position on the other first end ring through a first cage leg along the axial direction.

[0043] As an implementation method, the first birdcage coil 1 includes eight cage legs and eight first distributed capacitors 3, and the second birdcage coil 2 includes four second distributed capacitors 4 and four third distributed capacitors 5, as well as four pairs of staggered second cage legs.

[0044] The system also includes a matching circuit for the first birdcage coil 1, which includes a first tuning capacitor 6 and a pair of first matching capacitors 8. One of the first distributed capacitors 3 on the first birdcage coil 1 is selected as a port capacitor. The two ends of the port capacitor of the first birdcage coil 1 connected in parallel with the first tuning capacitor 6 are respectively connected in series with one end of a first matching capacitor 8. The other ends of the two first matching capacitors 8 are connected to the output port of the H-channel radio frequency power amplifier of the MRI radio frequency system.

[0045] Under the monitoring of the vector network analyzer, the first tuning capacitor 6 and the first matching capacitor 8 are adjusted to make the 400MHz reflection coefficient S 11 (400MHz) <-20dB. Note that in this step, the 8-leg high-pass birdcage coil has five different resonance points in the vector network analyzer, and only the second-highest resonance point is correct and effective.

[0046] It also includes a shielding cover that is sleeved on the outside of the first birdcage coil 1. The shielding cover includes multiple identical copper shielding strips parallel to the axial direction. All shielding strips are evenly spaced along the circumferential direction. There are gaps between adjacent shielding strips. Gap capacitors are provided in the gaps between adjacent shielding strips. As a feasible implementation method, the gaps between adjacent shielding strips are less than 1 mm, and the gap capacitance is 1-10 nF. Leaving gaps between adjacent shielding strips can suppress eddy currents induced by gradients under working conditions, and providing gap capacitance can enhance the shielding level of the shielding cover in the frequency band of hundreds of MHz.

[0047] The ratio of the inner and outer diameters of traditional nested birdcage solutions is generally around 70% to 75%. However, simulation results of the nested birdcage coils of the present invention show that this modification can make the inner second birdcage coil 1 and the outer first birdcage coil 2 almost the same diameter.

[0048] Example 2:

[0049] A method for manufacturing a multi-nuclide magnetic resonance excitation coil comprises the following steps:

[0050] This example is used for topological optimization of a 9.4T MRI scanner. 129 Xe / 1 H MRI excitation coil fabrication;

[0051] This embodiment is a specific implementation of the present invention under a 9.4T MRI scanner. 129 Xe channel, outer layer 1 The production process of the H-channel topology-optimized dual-core MRI excitation coil includes the following steps:

[0052] Step 1: Construct a shielding case by axially attaching copper shielding strips (copper foil tape is used for the shielding strips in this embodiment) with a width of 20 mm and a thickness of not less than 50 μm to the inner cylindrical surface of a first support tube with an inner diameter of 114 mm, an outer diameter of 120 mm, and a length of 290 mm. The gap between adjacent copper foil tapes is less than 1 mm, and a gap capacitor of 1-10 nF is set in the gap between adjacent shielding strips.

[0053] Step 2: Construct a first birdcage coil 1. The first birdcage coil 1 is arranged on the outer cylindrical surface of a second support tube with an inner diameter of 90 mm, an outer diameter of 96 mm, and a length of 290 mm. The first end ring segment and the first cage leg are both pasted with a copper foil tape with a width of 7 mm and a thickness of not less than 50 μm and are arranged on the outer cylindrical surface of the second support tube. A first distributed capacitor 3 of 4 pF is welded between each adjacent end ring segment of the two end rings. The length of the first birdcage coil 1 is 114 mm.

[0054] Step 3, construct a second birdcage coil 2, the second birdcage coil 2 is set on the outer cylindrical surface of the third support tube with an inner diameter of 72mm, an outer diameter of 78mm, and a length of 290mm, and the second sub-end ring segments are all set on the outer cylindrical surface of the third support tube by pasting with copper foil tape with a width of 5mm and a thickness of not less than 50μm. A second distributed capacitor 4 of 25pF is welded between each end ring segment, and a third distributed capacitor 5 is welded between the two sub-end ring segments of each end ring segment; an annular exchange plate is set in the middle position between the two second end rings, and a plurality of connection hole groups penetrating the end surface ring walls on both sides are set on the exchange plate. Each connection hole group is evenly distributed along the circumferential direction of the exchange plate, and each connection hole group includes two connection holes of the same length, which are respectively recorded as a first connection hole 10 and a second connection hole 11. The first connection hole 10 and the second connection hole 11 are respectively provided with a first connection line and a second connection line;

[0055] Use hot melt adhesive to secure the annular exchange plate to the center of the outer cylindrical surface of the third support tube. For each pair of second cage legs, two copper foil tapes with a width of 5 mm and a thickness of no less than 50 μm are used for the second cage legs. One end of the two copper foil tapes of one second cage leg is connected to the two ends of the first connecting wire, and the other end is connected to the second sub-end ring segment corresponding to one end ring and the first sub-end ring segment corresponding to the other end ring. One end of the two copper foil tapes of the other second cage leg is connected to the two ends of the second connecting wire, and the other end is connected to the first sub-end ring segment corresponding to one end ring and the second sub-end ring segment corresponding to the other end ring, forming an "8"-shaped staggered connection.

[0056] Unlike traditional nested birdcage solutions, the second birdcage coil 2 of the present invention uses a switching circuit to structurally swap adjacent cage leg structures, thereby constructing an "8"-shaped loop in the circuit with half the number of original birdcage legs. After the two cage legs are connected in positive sequence from one side, they can be output in reverse sequence from the other side. For the two cage legs that are swapped with each other, the routing lengths of the two legs in the switching board are equal.

[0057] As an implementation method, the first support tube, the second support tube, and the third support tube are all made of epoxy resin tubes.

[0058] Step 4: Perform impedance matching on the first birdcage coil 1: Select a first distributed capacitor 3 on the first birdcage coil 1 as a port capacitor. The two ends of the port capacitor of the first birdcage coil 1 connected in parallel with the first tuning capacitor 6 are respectively connected in series to one end of a first matching capacitor 8. The other ends of the two first matching capacitors 8 are connected to the output port of the H-channel RF power amplifier of the MRI RF system.

[0059] Perform impedance matching on the second birdcage coil 2: select a second distributed capacitor 4 on the second birdcage coil 2 as the port capacitor, and connect the two ends of the port capacitor of the second birdcage coil 2 in parallel with the second tuning capacitor 7 to one end of a second matching capacitor 9 in series. The other ends of the two second matching capacitors 9 are connected to the port for connecting to the MRI radio frequency system. 129 Output port of the Xe channel broadband RF power amplifier.

[0060] Step 5: Adjust the circumferential relative positions of the shielding cover, the first birdcage coil 1, and the second birdcage coil 2: Use the end caps made by 3D printing to fix the shielding cover, the first birdcage coil 1, and the second birdcage coil 2, and adjust the circumferential relative positions of the shielding cover, the first birdcage coil 1, and the second birdcage coil 2 by rotating them one by one so that the transmission coefficient S in the vector network analyzer is 12 (110MHz) and S 12 (400MHz) are not higher than -20dB; then use the studs to lock the relative positions.

[0061] Figure 8The following figure compares the axial RF field strength (at 1W input power) of a single outer birdcage coil, a conventional nested birdcage coil, and the topologically optimized nested birdcage coil of the present invention. The topologically optimized nested birdcage coil of the present invention exhibits the strongest RF field. The field intensity at the center point is nearly identical between the single outer birdcage coil and the topologically optimized nested birdcage coil. This demonstrates that in the topologically optimized nested birdcage coil, the inner second birdcage coil 2 is "transparent" relative to the outer first birdcage coil 1, allowing the RF field to pass through the inner second birdcage coil 2 without loss to reach the sample.

[0062] It should be noted that the embodiments described herein are merely illustrative of the spirit of the present invention. Persons skilled in the art may make various modifications, additions, or substitutions to the described embodiments without departing from the spirit of the present invention or exceeding the scope of the appended claims.

Claims

1. A multi-nuclide magnetic resonance excitation coil, comprising a first birdcage coil (1) and a second birdcage coil (2) arranged in a nested manner, wherein the second birdcage coil (2) is embedded in the first birdcage coil (1), characterized in that: The second birdcage coil (2) comprises a pair of parallel second end rings, each second end ring comprises a plurality of identical second end ring segments, each second end ring segment comprises an identical first sub-end ring segment and a second sub-end ring segment, the second end ring segment on one second end ring is connected to the second end ring segment corresponding to the position on another second end ring via a second cage leg pair, the second cage leg pair comprises two staggered second cage legs, the first sub-end ring segment of the second end ring segment on one second end ring is connected to the second sub-end ring segment of the second end ring segment corresponding to the position on another second end ring via a second cage leg, and the second sub-end ring segment of the second end ring segment on one second end ring is connected to the first sub-end ring segment of the second end ring segment corresponding to the position on another second end ring via a second cage leg.

2. The multi-nuclide magnetic resonance excitation coil according to claim 1, characterized in that: A second distributed capacitor (4) is provided between adjacent second end ring segments, and a third distributed capacitor (5) is provided between the first sub-end ring segment and the second sub-end ring segment of each second end ring segment. The second distributed capacitor (4) and the third distributed capacitor (5) have different capacitance values.

3. The multi-nuclide magnetic resonance excitation coil according to claim 2, characterized in that: The invention also includes a matching circuit for a second birdcage coil (2), wherein the matching circuit for the second birdcage coil (2) includes a second tuning capacitor (7) and a pair of second matching capacitors (9), wherein a second distributed capacitor (4) on the second birdcage coil (2) serves as a port capacitor, and the two ends of the port capacitor of the second birdcage coil (2) connected in parallel with the second tuning capacitor (7) are respectively connected in series with one end of a second matching capacitor (9), and the other ends of the two second matching capacitors (9) are led out of the port.

4. The multi-nuclide magnetic resonance excitation coil according to claim 1, characterized in that: The first birdcage coil (1) comprises a pair of parallel first end rings, a plurality of first distributed capacitors (3) are arranged on the first end rings at equal intervals along the circumferential direction, each first distributed capacitor (3) divides the first end ring into a plurality of identical first end ring segments, and each first end ring segment of one first end ring is connected to each first end ring segment corresponding to a position on the other first end ring via a first cage leg along the axial direction.

5. The multi-nuclide magnetic resonance excitation coil according to claim 4, characterized in that: The invention also includes a matching circuit for the first birdcage coil (1), wherein the matching circuit for the first birdcage coil (1) includes a first tuning capacitor (6) and a pair of first matching capacitors (8), wherein a first distributed capacitor (3) on the first birdcage coil (1) serves as a port capacitor, and the two ends of the port capacitor of the first birdcage coil (1) connected in parallel with the first tuning capacitor (6) are respectively connected in series with one end of a first matching capacitor (8), and the other ends of the two first matching capacitors (8) are led out of the port.

6. The multi-nuclide magnetic resonance excitation coil according to claim 1, characterized in that: It also includes a shielding cover sleeved on the outside of the first birdcage coil (1), the shielding cover including a plurality of identical shielding strips parallel to the axial direction, all the shielding strips being distributed at equal intervals along the circumferential direction, gaps being left between adjacent shielding strips, and gap capacitors being provided in the gaps between adjacent shielding strips.

7. A method for manufacturing a multi-nuclide magnetic resonance excitation coil, characterized in that: The following steps are involved: Step 1: Build a shielding cover, and stick shielding strips on the inner cylindrical surface of the first support tube along the axial direction. The gap between adjacent copper foil tapes is smaller than the first set gap, and gap capacitance is set in the gap between adjacent shielding strips. Step 2: constructing a first birdcage coil (1), wherein the first birdcage coil (1) is arranged on the outer cylindrical surface of the second support tube, the first end ring segment and the first cage leg are both adhered to the outer cylindrical surface of the second support tube using copper foil tape, and a first distributed capacitor (3) is welded between each adjacent end ring segment of the two end rings; Step 3, constructing a second birdcage coil (2), the second birdcage coil (2) is arranged on the outer cylindrical surface of the third support tube, the second sub-end ring segments are all attached to the outer cylindrical surface of the third support tube by copper foil tape, the second distributed capacitor (4) is welded between each end ring segment, and the third distributed capacitor (5) is welded between the two sub-end ring segments of each end ring segment; an annular exchange plate is arranged in the middle position between the two second end rings, and the exchange plate is provided with a plurality of connection hole groups penetrating the ring walls of the end faces on both sides, and each connection hole group is evenly distributed along the circumferential direction of the exchange plate, and each connection hole group includes a first connection hole (10) and a second connection hole (11) of the same length, and the first connection hole (10) and the second connection hole (11) are respectively provided with a first connection line and a second connection line; An annular exchange plate is fixed to the center of the outer cylindrical surface of the third support tube. For each pair of second cage legs, one end of the two copper foil tapes of one second cage leg is respectively connected to the two ends of the first connecting line, and the other end is respectively connected to the second sub-end ring segment corresponding to one end ring and the first sub-end ring segment corresponding to the other end ring; one end of the two copper foil tapes of the other second cage leg is respectively connected to the two ends of the second connecting line, and the other end is respectively connected to the first sub-end ring segment corresponding to one end ring and the second sub-end ring segment corresponding to the other end ring.

8. The method for manufacturing a multi-nuclide magnetic resonance excitation coil according to claim 7, characterized in that: The following steps are also included: Step 4: perform impedance matching on the first birdcage coil (1) and the second birdcage coil (2) respectively.

9. The method for manufacturing a multi-nuclide magnetic resonance excitation coil according to claim 8, characterized in that: The following steps are also included: Step 5, adjusting the circumferential relative positions of the shielding cover, the first birdcage coil (1), and the second birdcage coil (2): fix the shielding cover, the first birdcage coil (1), and the second birdcage coil (2), and adjust the circumferential relative positions of the shielding cover, the first birdcage coil (1), and the second birdcage coil (2) by rotating them one by one, and then lock them with studs.

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