Local radio frequency shimming coil and shimming method

Abstract

The invention relates to the technical field of medical instruments, and provides a local radio frequency shimming coil and a shimming method.The local radio frequency shimming coil comprises a coil unit and a tuning circuit; the coil unit at least comprises a first coil unit and a second coil unit which are adjacently arranged and have a common side, and the tuning circuit is connected with the common side; when the local radio frequency shimming coil is in a shimming mode, the tuning circuit is in a detuning state, so that the first coil unit and the second coil unit are combined into a shimming loop; when the local radio frequency shim coil is in a signal receiving mode, the tuning circuit is in a tuning state, so that the first coil unit and the second coil unit are respectively used as receiving loops for receiving magnetic resonance signals. In the invention, the local radio frequency shimming coil has a shimming mode and a signal receiving mode, the modes can be flexibly switched on the basis of use requirements, and in the shimming mode, the coil units can be flexibly combined on the basis of the use requirements so as to adjust the size of the shimming coil.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and in particular to a local radio frequency shimming coil and a shimming method. Background Art

[0002] Magnetic resonance imaging is a technology widely used in medical imaging to display the structure of the human body or biological tissue. It has the advantages of high image resolution, high soft tissue contrast, arbitrary multi-directional imaging, rich imaging parameters and no ionizing radiation.

[0003] In medical imaging equipment, a transmission field is generated by a radio frequency transmitting coil to excite specific elements. The transmission field causes the protons in the human body to flip, and the signal of proton relaxation recovery is received by the receiving coil. As the field strength increases, the wavelength becomes shorter and shorter, and it becomes increasingly difficult to obtain a uniform transmission radio frequency field. In addition, due to the influence of the structure of human tissue, black holes are likely to appear in local areas during the imaging process, such as near the liver lobe.

[0004] In order to solve the above technical problems, a commonly used method at present is to add a local radio frequency shim coil.

[0005] The existing shimming coil setting method is usually to match one receiving coil with one local RF shimming coil. The size of the local RF shimming coil in this setting method is restricted by the receiving coil, and the size of the local RF shimming coil can only be the size of the receiving coil. For example, under the requirement of a high-channel magnetic resonance coil, the size of a single receiving coil is small, which leads to the size of the local RF shimming coil being small. At this time, the shimming function of the local RF shimming coil is limited. In addition, the setting method of matching one receiving coil with one local RF shimming coil one by one makes the entire coil structure more complicated.

[0006] Therefore, based on the above technical problem, the present invention proposes a coil design solution shared by a local radio frequency shim coil antenna and a receiving coil antenna. Summary of the invention

[0007] The object of the present invention is to provide a local radio frequency shimming coil and a shimming method; the local radio frequency shimming coil has a shimming mode and a signal receiving mode, and its mode can be flexibly switched based on usage requirements, and in the shimming mode, coil units can be flexibly merged based on its usage requirements to adjust the size of the shimming coil.

[0008] The present invention provides a local radio frequency shimming coil.

[0009] including a coil unit and a tuning circuit;

[0010] The coil unit at least includes a first coil unit and a second coil unit that are adjacently arranged;

[0011] The first coil unit and the second coil unit have a common side;

[0012] The tuning circuit is connected to the common edge, and the tuning circuit has a tuning state and a detuning state;

[0013] The local radio frequency shimming coil has a shimming mode and a signal receiving mode;

[0014] When the local radio frequency shim coil is in shim mode, the tuning circuit is in a detuned state, so that the portion of the first coil unit excluding the common edge and the portion of the second coil unit excluding the common edge are combined into a shim loop;

[0015] When the local radio frequency shim coil is in a signal receiving mode, the tuning circuit is in a tuning state, so that the first coil unit serves as a first receiving loop and the second coil unit serves as a second receiving loop, and the first receiving loop and the second receiving loop are used to receive magnetic resonance signals.

[0016] Optionally, the local radio frequency shimming coil further includes an output circuit;

[0017] The output circuit is connected to the coil unit; the output circuit has a circuit state and an open circuit state;

[0018] When the local radio frequency shimming coil is in the shimming mode, the output circuit is in the open circuit state;

[0019] When the local radio frequency shim coil is in the signal receiving mode, the output circuit is in the on state.

[0020] Optionally, when the tuning circuit is in a tuning state, the resonant path where the common edge is located is in a connection state; when the tuning circuit is in a detuning state, the resonant path where the common edge is located is in an open state.

[0021] Optionally, the local radio frequency shimming coil further includes a shimming power input circuit, which is connected to the coil unit and is used to provide radio frequency power to the coil unit connected thereto in the shimming mode.

[0022] Optionally, the shim power input circuit includes an input source and an input capacitor, wherein the input source and the input capacitor are connected in series and connected to a coil unit having a common side.

[0023] Optionally, the shim power input circuit further includes an input diode, the input diode is connected in series with the input source and the input capacitor, and an anode of the input diode is connected to the input source.

[0024] Optionally, the tuning circuit includes a common capacitor, a tuning inductor and a tuning diode, the common capacitor is connected in series within the common edge, the tuning inductor is connected in series with the tuning diode, and a series loop of the tuning inductor and the tuning diode is connected in parallel with the common capacitor.

[0025] Optionally, the output circuit includes an output capacitor, an output inductor and a first output diode, the output capacitor is connected to the coil unit, the output inductor is connected in series with the first output diode, and a series loop of the output inductor and the first output diode is connected in parallel with the output capacitor.

[0026] Optionally, the output circuit also includes a second output diode, which is connected in series with the output inductor and the first output diode, and the series circuit of the output inductor, the first output diode and the second output diode is connected in parallel with the output capacitor; one pole of the output capacitor is connected to the coil unit, and the other pole is connected to the positive pole of the second output diode, and the cathode of the second output diode is connected to the cathode of the first output diode.

[0027] The present invention also provides a shimming method for a magnetic resonance system.

[0028] The magnetic resonance system comprises a radio frequency transmitting coil and a local radio frequency shimming coil, wherein the local radio frequency shimming coil comprises at least a first coil unit and a second coil unit arranged adjacent to each other and a tuning circuit;

[0029] The first coil unit and the second coil unit have a common side;

[0030] The common edge is connected to the tuning circuit, and the tuning circuit has a tuning state and a detuning state;

[0031] The shimming method comprises the following steps:

[0032] The radio frequency transmitting coil transmits radio frequency pulses and puts the tuning circuit in a detuned state, so that the portion of the first coil unit excluding the common edge and the portion of the second coil unit excluding the common edge are combined into a shim loop to form a local radio frequency field;

[0033] The RF transmitting coil stops transmitting RF pulses and puts the tuning circuit into a tuning state, so that the first coil unit forms a first receiving loop and the second coil unit forms a second receiving loop; the first receiving loop and the second receiving loop are used to receive magnetic resonance signals.

[0034] Optionally, the operating frequency of the local radio frequency shimming coil when forming the local radio frequency field is the same as the frequency at which the radio frequency transmitting coil transmits radio frequency pulses.

[0035] In summary, the local radio frequency shim coil comprises a coil unit and a tuning circuit; the coil unit comprises at least a first coil unit and a second coil unit arranged adjacent to each other; the first coil unit and the second coil unit have a common edge; the tuning circuit is connected to the common edge, and the tuning circuit has a tuning state and a detuning state; the local radio frequency shim coil has a shim mode and a signal receiving mode; when the local radio frequency shim coil is in the shim mode, the tuning circuit is in a detuning state, so that the part of the first coil unit excluding the common edge and the part of the second coil unit excluding the common edge are combined into a shim loop; when the local radio frequency shim coil is in the signal receiving mode, the tuning circuit is in a tuning state, so that the first coil unit serves as a first receiving loop, and the second coil unit serves as a second receiving loop, and the first receiving loop and the second receiving loop are used to receive magnetic resonance signals.

[0036] With such configuration, the local radio frequency shimming coil in the present invention has a shimming mode and a signal receiving mode, and its mode can be flexibly switched based on usage requirements.

[0037] When the RF transmitting coil generates an RF pulse, the local RF shim coil needs to be in a shim mode. In this mode, the common edge can be flexibly selected based on usage requirements, so that the tuning circuit corresponding to the common edge is in a detuned state, so that the part of the first coil unit excluding the common edge and the part of the second coil unit excluding the common edge are combined into a shim loop to form a large shim coil, so as to flexibly adjust the size of the shim coil.

[0038] When the local radio frequency shim coil needs to be used as a receiving coil, it is placed in a signal receiving mode, the tuning circuit is in a tuning state, so that the first coil unit is used as a first receiving loop, the second coil unit is used as a second receiving loop, and each coil unit is used as a multi-channel receiving coil to receive magnetic resonance signals, and the signals are output to the preamplifier input through the output circuit and the phase adjustment component.

[0039] The above-mentioned local RF shimming coil can adaptively adjust the number of sub-coil units based on different parts of the examination, as well as the number of sub-coil units with shared edges and the position of the sub-coil in the array to meet the shimming requirements during imaging of each part of the examination. And the number of shared edges can be flexibly set based on usage requirements, that is, the number of sub-coil units with shared edges can be adjusted. When there are multiple sub-coil units adjacent to each other and with shared edges, the corresponding number of shared edges can be selected to be in a detuned state based on the requirements of shimming, and then the size of the shimming coil can be adaptively adjusted. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1It is a structural schematic diagram of a local radio frequency shim coil according to the first embodiment of the present invention;

[0041] Figure 2 It is a structural schematic diagram of a local radio frequency shim coil according to a second embodiment of the present invention;

[0042] Figure 3 It is a structural schematic diagram of a local radio frequency shim coil according to Embodiment 3 of the present invention;

[0043] Figure 4 It is a structural schematic diagram of a local radio frequency shim coil according to a fourth embodiment of the present invention;

[0044] Figure 5 It is a schematic diagram of the structure of a local radio frequency shim coil according to Embodiment 5 of the present invention.

[0045] The reference numerals are as follows:

[0046] 10-coil unit; 11-conducting wire; 12-first capacitor; 13-second capacitor; 14-third capacitor;

[0047] 20- tuning circuit; 21- common capacitor; 22- tuning inductor; 23- tuning diode;

[0048] 30-output circuit; 31-output capacitor; 32-output inductor; 33-first output diode; 34-second output diode;

[0049] 40-uniform field power input circuit; 41-input source; 42-input capacitor; 43-input diode;

[0050] 50-phase modulation component;

[0051] 60-Preamplifier input. DETAILED DESCRIPTION

[0052] The local radio frequency shim coil proposed by the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0053] As used in the present invention, the singular forms "one", "an" and "the" include plural objects, the term "or" is usually used to include the meaning of "and / or", the term "several" is usually used to include the meaning of "at least one", and the terms "at least two" or "multiple" are usually used to include the meaning of "two or more". In addition, the terms "first", "second" and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" and "third" can explicitly or implicitly include one or at least two of the features. In addition, as used in the present invention, "installed", "connected", "connected", and one element "set" on another element should be understood in a broad sense, usually only indicating that there is a connection, coupling, matching or transmission relationship between the two elements, and the connection, coupling, matching or transmission between the two elements can be direct or indirect through an intermediate element, and cannot be understood as indicating or implying the spatial position relationship between the two elements, that is, one element can be in any orientation such as inside, outside, above, below or on one side of another element, unless the content clearly indicates otherwise. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, directional terms such as above, below, up, down, upward, downward, left, right, etc. are used with respect to the exemplary embodiments as they are shown in the figures, with the upward or upper direction toward the top of the corresponding figure, and the downward or lower direction toward the bottom of the corresponding figure.

[0054] Magnetic resonance imaging (MRI) is a technology widely used in medical imaging to display the structure of the human body or biological tissue. It has the advantages of high image resolution, high soft tissue contrast, arbitrary multi-directional imaging, rich imaging parameters and no ionizing radiation.

[0055] In medical imaging equipment, a transmission field is generated by a radio frequency transmitting coil to excite specific elements. The transmission field causes human protons to flip, and the signal of proton relaxation recovery is received by the receiving coil. As the field strength increases, the wavelength becomes shorter and shorter, and it becomes increasingly difficult to obtain a uniform transmission radio frequency field. Due to the influence of the structure of human tissue, black holes will appear in local areas during the imaging process, such as near the liver lobe.

[0056] In order to solve the above technical problems, a commonly used method at present is to add a local radio frequency shim coil.

[0057] The existing shimming setting method is usually to match one receiving coil with one local RF shimming coil. The size of the local RF shimming coil in this setting method is restricted by the receiving coil, and the size of the local RF shimming coil can only be the size of the receiving coil. For example, under the requirement of a high-channel magnetic resonance coil, the size of a single receiving coil is small, which leads to the size of the local RF shimming coil being small. At this time, the shimming function of the local RF shimming coil is limited. In addition, the setting method of matching one receiving coil with one local RF shimming coil one by one makes the entire coil structure more complicated.

[0058] Therefore, based on the above technical problem, the present invention proposes a coil design solution shared by a local radio frequency shim coil antenna and a receiving coil antenna.

[0059] Embodiment 1:

[0060] This embodiment provides a local radio frequency shimming coil, comprising: a plurality of coil units 10, a tuning circuit 20, and an output circuit 30;

[0061] The coil units 10 are arranged in an array, and the coil units 10 at least include a first coil unit 101 and a second coil unit 102 that are adjacent to each other; wherein the first coil unit 101 and the second coil unit 102 serve as sub-coil units.

[0062] The first coil unit 101 and the second coil unit 102 have a common edge;

[0063] Please refer to Figure 1 As shown, in this embodiment, the coil unit 10 includes two sub-coil units, namely a first coil unit 101 and a second coil unit 102, and the first coil unit 101 and the second coil unit 102 both resonate at a specified working frequency. Each sub-coil unit includes a resonant circuit formed by a wire 11 and a first capacitor 12, a second capacitor 13 and a third capacitor 14 connected in series to the wire 11, and the resonant frequency of the sub-coil unit is adjusted jointly by the first capacitor 12, the second capacitor 13 and the third capacitor 14. In this embodiment, the tuning circuit 20 includes a common capacitor 21, and the common capacitor 21 is set on the common side. At this time, the resonant frequency of the sub-coil unit is adjusted jointly by the first capacitor 12, the second capacitor 13, the third capacitor 14 and the common capacitor 21.

[0064] The capacitors connected in series in each sub-coil unit can be adaptively adjusted based on actual use requirements. At least one capacitor should be connected in series, and the output circuit 30 is connected to the two electrodes of one of the capacitors, such as Figure 1 As shown, in this embodiment, the output circuit 30 is connected to the two electrodes of the third capacitor 14.

[0065] At least one common edge is connected to the tuning circuit 20, and the tuning circuit 20 has a tuning state and a detuning state; when the tuning circuit 20 is in the tuning state, the resonant path where the common edge is located is in a pass state, and when the tuning circuit 20 is in the detuning state, the resonant path where the common edge is located is in an open state, so that the two sub-coil units with a common edge are combined into a uniform field loop.

[0066] Please continue to refer to Figure 1 As shown, the tuning circuit 20 includes a common capacitor 21, a tuning inductor 22 and a tuning diode 23. The common capacitor 21 is connected in series within the common edge, the tuning inductor 22 is connected in series with the tuning diode 23, and the series loop of the tuning inductor 22 and the tuning diode 23 is connected in parallel with the common capacitor 21.

[0067] Through the above-mentioned tuning circuit 20, the state of the tuning circuit 20 can be adjusted by controlling the on and off of the tuning diode 23. For example, when the tuning diode 23 is turned on, the shared capacitor 21 and the tuning inductor 22 form a parallel resonant circuit to form a high impedance. At this time, the resonant path where the shared edge is located is equivalent to an open circuit state. At this time, the first coil unit 101 with the portion of the shared edge removed and the second coil unit 102 with the portion of the shared edge removed are combined into a uniform field loop, so that the size of the coil can be adjusted. When the tuning diode 23 is turned off, the shared tuning inductor 22 does not participate in the work. At this time, the resonant path where the shared edge is located is equivalent to a pass state. At this time, the first coil unit 101 and the second coil unit 102 with the shared edge are respectively used as the first receiving loop and the second receiving loop for receiving magnetic resonance signals.

[0068] The on-off control of the tuning diode 23 can be connected to the external circuit control; when the external circuit provides a forward bias voltage to the tuning diode 23, the tuning diode 23 is turned on, and when the external circuit provides a reverse bias voltage less than its Zener voltage to the tuning diode 23, the tuning diode 23 is open. Alternatively, the on-off of the tuning diode 23 can be controlled by passive induction current. When the radio frequency transmitting coil in the magnetic resonance imaging system transmits a radio frequency pulse signal, the resonant circuit generates a passive induction current, and transmits the passive induction current to the tuning diode 23 to achieve adaptive control of the on-off of the tuning diode 23.

[0069] In this embodiment, the tuning diode 23 is preferably controlled by an external circuit to ensure its reliability.

[0070] Through the above-mentioned tuning circuit 20, not only the on-off of the resonant path where the common side is located can be controlled, but also when the tuning diode 23 is turned on, the resonant circuit composed of the common capacitor 21 and the tuning inductor 22 also serves as a protection circuit, which absorbs interference and protects the entire coil.

[0071] In other alternative embodiments, the tuning circuit 20 may also adopt other known circuit structures, for example, a switch structure suitable for electromagnetics may be adopted to control the on-off of the common side.

[0072] The output circuit 30 is connected to the sub-coil unit; the output circuit 30 has a closed circuit state and an open circuit state.

[0073] Please refer to Figure 1 As shown, each sub-coil unit is provided with an output circuit 30. Taking one of the sub-coil units as an example, the input end of the output circuit 30 is connected to the two electrodes of the third capacitor 14, the output end of the output circuit 30 is connected to the phase adjustment component 50, and the phase adjustment component 50 is connected to the preamplifier input 60.

[0074] Please continue to refer to Figure 1 As shown,

[0075] The first coil unit 101 and the second coil unit 102 are both connected to an output circuit 30;

[0076] Take the first coil unit 101 as an example for description.

[0077] The output circuit 30 includes an output capacitor 31, an output inductor 32 and a first output diode 33. One pole of the output capacitor 31 is connected to the first coil unit 101, and the other pole is connected to the phase adjustment component 50. The output inductor 32 is connected in series with the first output diode 33, and the series circuit of the output inductor 32 and the first output diode 33 is connected in parallel with the output capacitor 31.

[0078] The output circuit 30 also includes a second output diode 34, which is connected in series with the output inductor 32 and the first output diode 33. The series circuit of the output inductor 32, the first output diode 33 and the second output diode 34 is connected in parallel with the output capacitor 31; one pole of the output capacitor 31 is connected to the first coil unit 101, and the other pole is connected to the positive pole of the second output diode 34, and the negative pole of the second output diode 34 is connected to the negative pole of the first output diode 33.

[0079] Similarly, in this embodiment, the state of the output circuit 30 can be adjusted by controlling the on and off of the first output diode 33 and the second output diode 34. When the first output diode 33 and the second output diode 34 are turned on, the output capacitor 31 and the output inductor 32 form a parallel resonant circuit to form a high impedance. At this time, the resonant path where the output capacitor 31 is located is equivalent to an open circuit state, and the resonant signal of the coil unit 10 cannot be output through the output circuit 30; when one of the first output diode 33 and the second output diode 34 is turned off, the output inductor 32 does not participate in the work. At this time, the resonant path where the output capacitor 31 is located is equivalent to a pass state, and the resonant signal of the coil unit 10 can be output through the output circuit 30.

[0080] Similar to the tuning diode 23 , in this embodiment, preferably, the first output diode 33 and the second output diode 34 are controlled by an external circuit to ensure their reliability.

[0081] Through the above-mentioned output circuit 30, not only the state of the output circuit 30 can be adjusted to control the output of the resonant signal of the coil unit 10, but also when the first output diode 33 and the second output diode 34 are turned on, the resonant circuit composed of the output capacitor 31 and the output inductor 32 also serves as a protection circuit, which plays a role in absorbing interference and protecting the entire coil.

[0082] In other alternative embodiments, only the first output diode 33 may be provided without the second output diode 34. In this case, the on-off of the output circuit 30 may be controlled by the first output diode 33. In this embodiment, the second output diode 34 is added, and the cathodes of the first output diode 33 and the second output diode 34 are grounded. When the output circuit 30 is in the head-on state, the coil unit 10 outputs a magnetic resonance signal to the output circuit 30. By adding a reverse bias voltage to the second output diode 34 to cut it off, the magnetic resonance signal can be prevented from being grounded through the second output diode 34, thereby ensuring that the magnetic resonance signal is output to the preamplifier input 60 through the phase adjustment component 50.

[0083] The local radio frequency shimming coil has a shimming mode and a signal receiving mode;

[0084] When the local RF shim coil is in the shim mode, the output circuit 30 is in the open circuit state, so as to prevent the output of the resonant signal of the coil unit 10; in this mode, the state of the tuning circuit 20 is not limited, and the tuning circuit 20 can be in the open circuit state, so that each sub-coil unit acts as a shim coil, or the tuning circuit 20 can be in the on state, so that the two sub-coil units are combined into a resonant circuit to form a large shim coil.

[0085] When the local RF shim coil is in the signal receiving mode, the tuning circuit 20 is in the tuning state, and the output circuit 30 is in the pass state, for outputting the resonant signal of the coil unit 10. At this time, the resonant signal of the coil unit 10 is output through the output circuit 30.

[0086] The use principle of the above-mentioned local radio frequency shimming coil is as follows:

[0087] In the MRI system, the RF transmitting coil and the receiving coil work alternately. The RF transmitting coil generates RF pulses, which excite the hydrogen protons in the human body. The hydrogen protons in the examined part of the human body absorb energy and deflect and spin in one direction. After the RF pulse stops, nuclear magnetic relaxation begins, that is, the recovery process of hydrogen protons is called the relaxation process, and the time required to return to the original equilibrium state is called the relaxation time. During the relaxation process, hydrogen protons release the absorbed energy and return to the equilibrium state. The released electromagnetic energy is converted into magnetic resonance signals, which are then collected and output through the receiving coil.

[0088] The shim coil is used for radio frequency shimming and works synchronously with the radio frequency transmitting coil.

[0089] When the RF transmitting coil generates an RF pulse, the local RF shim coil needs to be in the shim mode. At this time, the external circuit provides a forward bias voltage to the first output diode 33 and the second output diode 34. The first output diode 33 and the second output diode 34 are turned on, and the output circuit 30 is in an open circuit state. The resonant path where the output capacitor 31 is located is equivalent to an open circuit state, and the resonant signal of the coil unit 10 cannot be output through the output circuit 30.

[0090] At this time, the tuning diode 23 can be turned on or off. When the external circuit provides a reverse bias voltage to the tuning diode 23, the tuning diode 23 is turned off, so that the tuning circuit 20 is in an open circuit state, and at this time, each sub-coil unit acts as a shim coil. When the external circuit provides a forward bias voltage to the tuning diode 23, the tuning diode 23 is turned on, so that the tuning circuit 20 is in a pass state, so that the two sub-coil units are combined into a shim loop to form a large shim coil. Therefore, the size of the shim coil can be flexibly adjusted through the tuning circuit 20.

[0091] After the RF transmitting coil generates the RF pulse, it stops generating the RF pulse. At this time, the local RF shim coil needs to be used as a receiving coil to receive the magnetic resonance signal of the relaxation process. At this time, the first output diode 33 and the second output diode 34 are turned off, and the output circuit 30 is in the pass state. The tuning diode 23 is turned off. At this time, the tuning circuit 20 is in the tuning state, so the resonant path where the common edge is located is in the pass state. Each sub-coil unit is used as a multi-path receiving coil to receive the magnetic resonance signal. The signal is output to the preamplifier input 60 through the output circuit 30 and the phase adjustment component 50. At this time, the second output diode 34 is turned off, which is also used to prevent the magnetic resonance signal from being output to the ground through the second output diode 34.

[0092] In this embodiment, a medical imaging device is also provided, the medical imaging device comprising the local radio frequency shimming coil described above. The medical imaging device may be an existing magnetic resonance imaging related device.

[0093] In summary, the local radio frequency shim coil of this embodiment includes a coil unit 10 and a tuning circuit 20; the coil unit 10 includes at least a first coil unit 101 and a second coil unit 102 that are adjacently arranged; the first coil unit 101 and the second coil unit 102 have a common edge; the tuning circuit 20 is connected to the common edge, and the tuning circuit 20 has a tuning state and a detuning state; the local radio frequency shim coil has a shim mode and a signal receiving mode; when the local radio frequency shim coil is in the shim mode, the tuning circuit 20 is in a detuning state, so that a portion of the first coil unit 101 excluding the common edge and a portion of the second coil unit 102 excluding the common edge are combined into a shim loop; when the local radio frequency shim coil is in the signal receiving mode, the tuning circuit 20 is in a tuning state, so that the first coil unit 101 serves as a first receiving loop, and the second coil unit 102 serves as a second receiving loop, and the first receiving loop and the second receiving loop are used to receive magnetic resonance signals.

[0094] With such configuration, the local radio frequency shimming coil in the present invention has a shimming mode and a signal receiving mode, and its mode can be flexibly switched based on usage requirements.

[0095] When the RF transmitting coil generates RF pulses, the local RF shim coil needs to be in shim mode, and the output circuit 30 is in an open circuit state, so the resonant signal of the coil unit 10 cannot be output through the output circuit 30. In this mode, the tuning circuit 20 can be in an open circuit state, and at this time, each sub-coil unit acts as a shim coil; or the common edge can be flexibly selected based on the use requirements, so that the tuning circuit 20 corresponding to the common edge is in a pass state, so that the multiple sub-coil units corresponding to the common edge are combined into a shim loop to form a large shim coil, so as to flexibly adjust the size of the shim coil.

[0096] When the local RF shim coil needs to be used as a receiving coil, it is placed in a signal receiving mode. At this time, the output circuit 30 is in the pass state, and the tuning circuit 20 is in the tuning state. Therefore, the resonant path where the common edge is located is in the pass state. Each sub-coil unit is used as a multi-pass receiving coil to receive a magnetic resonance signal. The signal is output to the preamplifier input 60 through the output circuit 30 and the phase adjustment component 50.

[0097] The above-mentioned local RF shimming coil can adaptively adjust the number of sub-coil units based on different parts of the examination, as well as the number of sub-coil units with shared edges and the position of the coil in the array to meet the shimming requirements during imaging of each part of the examination. And the number of shared edges can be flexibly set based on usage requirements, that is, the number of sub-coil units with shared edges can be adjusted. When there are multiple sub-coil units adjacent to each other and with shared edges, the resonant paths where the corresponding number of shared edges are located can be selected to be in an open circuit state based on the requirements of shimming, and then the size of the shimming coil can be adaptively adjusted.

[0098] This embodiment also provides a shimming method for a magnetic resonance system.

[0099] The magnetic resonance system comprises a radio frequency transmitting coil and a local radio frequency shimming coil, wherein the local radio frequency shimming coil comprises at least a first coil unit 101 and a second coil unit 102 arranged adjacent to each other and a tuning circuit 20;

[0100] The first coil unit 101 and the second coil unit 102 have a common edge;

[0101] The common edge is connected to the tuning circuit 20, and the tuning circuit 20 has a tuning state and a detuning state;

[0102] The shimming method comprises the following steps:

[0103] The RF transmitting coil transmits RF pulses, and the operating frequency of the local RF shim coil when forming a local RF field is the same as the frequency of the RF transmitting coil transmitting RF pulses; and the tuning circuit 20 is in a detuned state, so that the first coil unit 101, the part excluding the common edge, and the second coil unit 102, the part excluding the common edge, are combined into a shim loop to form a local RF field; at this time, the two sub-coil units are combined into a large shim coil, and the corresponding resonant circuit where the common edge is located is selected to be in an open circuit state based on the needs, so that multiple sub-coil units can be flexibly combined into a large shim coil, which can flexibly meet the shim requirements. The control of the open circuit and the passage state of the resonant circuit where the common edge is located can be implemented by the tuning circuit 20 described above.

[0104] The RF transmitting coil stops transmitting RF pulses and puts the tuning circuit 20 in a tuning state, so that the first coil unit 101 forms a first receiving loop and the second coil unit 102 forms a second receiving loop; the first receiving loop and the second receiving loop are used to receive magnetic resonance signals and output them through the output circuit. The output circuit can be turned on and off by the output circuit 30 described above.

[0105] Embodiment 2:

[0106] The difference between this embodiment and the first embodiment is that a shimming power input circuit 40 is added in this embodiment, so that the coil unit 10 is an active shimming coil when used as a shimming coil.

[0107] Please refer to Figure 2 As shown, the local RF shimming coil further includes a shimming power input circuit 40, which is connected to at least one sub-coil unit. The shimming power input circuit 40 is used to provide RF power to the coil unit 10 connected thereto in the shimming mode.

[0108] Please continue to refer to Figure 2 As shown, the shimming power input circuit 40 includes an input source 41 and an input capacitor 42, the input source 41 and the input capacitor 42 are connected in series and connected to the first coil unit 101. The input capacitor 42 is used to block the effect of direct current. When the local RF shimming coil is used as a shimming coil, the shimming power is fed into the coil unit through the input source 41 to achieve the purpose of active shimming.

[0109] Furthermore, the shim power input circuit 40 further includes an input diode 43, which is connected in series with the input source 41 and the input capacitor 42, and the anode of the input diode 43 is connected to the input source 41. The input capacitor 42 is also switched on and off by an external power controller.

[0110] When the local RF shim coil is used as a shim coil, when the external circuit provides a forward bias voltage to the input diode 43, the input diode 43 is turned on, and the shim power of the input source 41 can be fed into the coil unit; when the local RF shim coil is used as a receiving coil, when the external circuit provides a reverse bias voltage to the input diode 43, the input diode 43 is turned off, and the shim power of the input source 41 cannot be fed into the coil unit.

[0111] Embodiment three:

[0112] The difference between this embodiment and the first embodiment lies in the difference in the number of sub-coil units included in the coil unit 10 and the difference in the number of sub-coil units having a common side.

[0113] In the first embodiment, the coil unit 10 includes two sub-coil units, namely a first coil unit 101 and a second coil unit 102 . The two sub-coil units have a common side, so there are also two sub-coil units having a common side.

[0114] Please refer to Figure 3 As shown, in this embodiment, the coil unit 10 is provided with three sub-coil units, the three sub-coil units are arranged in one direction, and any two adjacent sub-coil units have a common edge, so the number of sub-coil units with a common edge is three.

[0115] In this embodiment, the output circuit 30 and the input circuit 40 are not shown, and only a portion of the tuning circuit 20 is shown.

[0116] When the local RF shimming coil is used as a shimming coil, any one or two common sides can be selected based on the shimming requirement so that the resonant path where the common side is located is in an open circuit state, so as to flexibly adjust the size of the shimming coil.

[0117] For example, if any resonance path where one of the shared edges is located is in an open circuit state, any two adjacent sub-coil units can be selected to be combined to form a large coil.

[0118] For another example, the resonant paths where two common sides are located may be selected to be in an open circuit state, so that three of the sub-coil units can be combined to form a large coil.

[0119] Embodiment 4:

[0120] The difference between this embodiment and the first embodiment lies in the difference in the number of sub-coil units included in the coil unit 10 and the difference in the number of sub-coil units having a common side.

[0121] In the first embodiment, the coil unit 10 includes two sub-coil units. The two sub-coil units have a common side, so there are also two sub-coil units having a common side.

[0122] Please refer to Figure 4 As shown, in this embodiment, the coil unit 10 includes four sub-coil units, which are arranged in one direction, and any two adjacent sub-coil units have a common edge, so the number of sub-coil units with a common edge is four.

[0123] In this embodiment, the output circuit 30 and the input circuit 40 are not shown, and only a portion of the tuning circuit 20 is shown.

[0124] When the local RF shimming coil is used as a shimming coil, any one, two or three common sides can be selected based on the shimming requirement so that the resonant path where the common side is located is in an open circuit state, so as to flexibly adjust the size of the shimming coil.

[0125] For example, if any resonance path where one of the shared edges is located is in an open circuit state, any two adjacent sub-coil units can be selected to be combined to form a large coil.

[0126] For another example, the resonant paths where two common sides are located can be selected to be in an open circuit state, so that three of the sub-coil units can be combined to form a large coil, or four of the sub-coil units can be combined in pairs to form two large coils.

[0127] For another example, the resonant paths where three common sides are located may be selected to be in an open circuit state, so that four of the sub-coil units can be combined to form a large coil.

[0128] In other alternative embodiments, more sub-coil units may be provided, and the number of shared edges may be flexibly provided based on the use requirements, that is, the number of sub-coil units with shared edges may be adjusted. When multiple sub-coil units are adjacent and have shared edges, the resonant paths where the corresponding number of shared edges are located may be selected to be in an open circuit state based on the requirements of shimming, thereby adaptively adjusting the size of the shimming coil.

[0129] Embodiment five:

[0130] The difference between this embodiment and the second embodiment lies in the number of sub-coil units included in the coil unit 10 .

[0131] Please refer to Figure 5 As shown, in this embodiment, a coil unit consisting of 24 channels and a 3×8 array is provided.

[0132] The resonant circuits in adjacent sub-coil units may be coupled to each other, which will affect the frequency of the resonant circuits in the sub-coil units. Therefore, in order to eliminate the mutual coupling between the resonant circuits in two adjacent sub-coil units, the resonant circuits of adjacent sub-coil units are combined in a partially overlapping manner; the overlapping area of ​​the partial overlap is pre-set, thereby eliminating the mutual coupling between the resonant circuits in two adjacent sub-coil units.

[0133] The unevenness of the transmission field and the influence of human tissue can cause imaging black holes. For example, black holes are likely to occur near the liver lobe. Therefore, a local RF shim coil needs to be constructed within the field of view covering the vicinity of the liver lobe. Figure 5 As shown, there is a common edge between two adjacent sub-coil units at corresponding positions, and a common capacitor 21 is arranged on the common edge. Correspondingly, an output circuit 30, an input circuit 40 and a tuning circuit 20 are also included; in this embodiment, the output circuit 30 and the input circuit 40 are not shown, and only a part of the tuning circuit 20 is shown.

[0134] When the RF transmitting coil generates RF pulses, the transmitting field near the liver lobe is composed of the transmitting field of the RF transmitting coil and the field of the local shim coil, and the RF power amplitude and phase of the local shim coil can be adjusted by the input circuit 40 to make the transmitting field near the liver lobe uniform.

[0135] In other alternative embodiments, the examined part may be the abdomen, head, joints, etc. Based on the different examined parts, the number of sub-coil units with shared edges and their positions in the array can be adaptively adjusted to meet the field uniformity requirements during imaging of each examined part.

[0136] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0137] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A local radio frequency shimming coil, characterized in that: It comprises a coil unit (10) and a tuning circuit (20); The coil unit (10) comprises at least a first coil unit (101) and a second coil unit (102) which are arranged adjacent to each other; The first coil unit (101) and the second coil unit (102) have a common edge; The tuning circuit (20) is connected to the common edge, and the tuning circuit (20) has a tuning state and a detuning state; The local radio frequency shimming coil has a shimming mode and a signal receiving mode; When the local radio frequency shim coil is in shim mode, the tuning circuit (20) is in a detuned state, so that the portion of the first coil unit (101) excluding the common edge and the portion of the second coil unit (102) excluding the common edge are combined into a shim loop; When the local radio frequency shim coil is in a signal receiving mode, the tuning circuit (20) is in a tuning state, so that the first coil unit (101) serves as a first receiving loop and the second coil unit (102) serves as a second receiving loop, and the first receiving loop and the second receiving loop are used to receive magnetic resonance signals.

2. The local radio frequency shimming coil according to claim 1, characterized in that: The local radio frequency shimming coil also includes an output circuit (30); The output circuit (30) is connected to the coil unit (10); the output circuit (30) has a closed circuit state and an open circuit state; When the local radio frequency shimming coil is in shimming mode, the output circuit (30) is in the open circuit state; When the local radio frequency shim coil is in the signal receiving mode, the output circuit (30) is in the on state.

3. The local radio frequency shimming coil according to claim 1, characterized in that: The local radio frequency shimming coil further comprises a shimming power input circuit (40), the shimming power input circuit (40) being connected to the coil unit (10), and the shimming power input circuit (40) being used to provide radio frequency power to the coil unit (10) connected thereto in the shimming mode.

4. The local radio frequency shimming coil according to claim 3, characterized in that: The shim power input circuit (40) comprises an input source (41) and an input capacitor (42); the input source (41) and the input capacitor (42) are connected in series and connected to a coil unit having a common edge.

5. The local radio frequency shimming coil according to claim 4, characterized in that: The shim power input circuit (40) further comprises an input diode (43), wherein the input diode (43) is connected in series with the input source (41) and the input capacitor (42), and an anode of the input diode (43) is connected to the input source (41).

6. The local radio frequency shimming coil according to claim 1, characterized in that: The tuning circuit (20) comprises a common capacitor (21), a tuning inductor (22) and a tuning diode (23); the common capacitor (21) is connected in series within the common edge; the tuning inductor (22) and the tuning diode (23) are connected in series; and a series loop of the tuning inductor (22) and the tuning diode (23) is connected in parallel with the common capacitor (21).

7. The local radio frequency shimming coil according to claim 1, characterized in that: The output circuit (30) comprises an output capacitor (31), an output inductor (32) and a first output diode (33); the output capacitor (31) is connected to the coil unit (10); the output inductor (32) is connected in series with the first output diode (33); and a series circuit of the output inductor (32) and the first output diode (33) is connected in parallel with the output capacitor (31).

8. The local radio frequency shimming coil according to claim 7, characterized in that: The output circuit (30) further comprises a second output diode (34), the second output diode (34) being connected in series with the output inductor (32) and the first output diode (33), and the series circuit of the output inductor (32), the first output diode (33) and the second output diode (34) being connected in parallel with the output capacitor (31); one pole of the output capacitor (31) is connected to the coil unit (10), and the other pole is connected to the positive pole of the second output diode (34), and the negative pole of the second output diode (34) is connected to the negative pole of the first output diode (33).

9. A method for shimming a magnetic resonance system, characterized in that: The magnetic resonance system comprises a radio frequency transmitting coil and a local radio frequency shimming coil, wherein the local radio frequency shimming coil comprises at least a first coil unit (101) and a second coil unit (102) arranged adjacent to each other and a tuning circuit (20); The first coil unit (101) and the second coil unit (102) have a common edge; The common edge is connected to the tuning circuit (20), and the tuning circuit (20) has a tuning state and a detuning state; The shimming method comprises the following steps: The radio frequency transmitting coil transmits radio frequency pulses and puts the tuning circuit (20) in a detuned state, so that the portion of the first coil unit (101) excluding the common edge and the portion of the second coil unit (102) excluding the common edge are combined into a shim loop to form a local radio frequency field; The radio frequency transmitting coil stops transmitting radio frequency pulses and puts the tuning circuit (20) into a tuning state, so that the first coil unit (101) forms a first receiving loop and the second coil unit (102) forms a second receiving loop; the first receiving loop and the second receiving loop are used to receive magnetic resonance signals.

10. The shimming method according to claim 9, characterized in that: The operating frequency of the local radio frequency shimming coil when forming the local radio frequency field is the same as the frequency at which the radio frequency transmitting coil transmits radio frequency pulses.

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