Radio frequency system and radio frequency control method for magnetic resonance imaging and magnetic resonance imaging system
阅读说明:本技术 磁共振成像的射频系统和射频控制方法及磁共振成像系统 (Radio frequency system and radio frequency control method for magnetic resonance imaging and magnetic resonance imaging system ) 是由 邢昊洋 仝盛 汤伟男 黄海 刘渝 路雪莲 于 2018-09-12 设计创作,主要内容包括:本发明提供一种磁共振成像的射频系统和射频控制方法及磁共振成像系统。该射频系统包括射频发生器、功率放大器、发射线圈、以及射频检测部件。所述射频发生器用于产生射频脉冲信号。所述功率放大器用于对所述射频脉冲信号进行放大处理并输出放大的射频脉冲信号。所述发射线圈用于接收所述放大的射频脉冲信号以向检测对象发射射频脉冲信号。所述射频检测部件用于检测所述发射线圈发射的射频脉冲信号,所述射频检测部件检测的射频脉冲信号用于反馈控制输入至所述发射线圈的射频脉冲信号。(The invention provides a radio frequency system and a radio frequency control method for magnetic resonance imaging and a magnetic resonance imaging system. The radio frequency system includes a radio frequency generator, a power amplifier, a transmit coil, and a radio frequency detection component. The radio frequency generator is used for generating a radio frequency pulse signal. The power amplifier is used for amplifying the radio frequency pulse signal and outputting the amplified radio frequency pulse signal. The transmitting coil is used for receiving the amplified radio frequency pulse signal to transmit the radio frequency pulse signal to a detection object. The radio frequency detection component is used for detecting a radio frequency pulse signal transmitted by the transmitting coil, and the radio frequency pulse signal detected by the radio frequency detection component is used for feedback control of the radio frequency pulse signal input to the transmitting coil.)
1. A radio frequency system for magnetic resonance imaging, comprising:
a radio frequency generator for generating a radio frequency pulse signal;
the power amplifier is used for amplifying the radio frequency pulse signal and outputting the amplified radio frequency pulse signal;
a transmitting coil for receiving the amplified radio frequency pulse signal to transmit the radio frequency pulse signal to a detection object; and
and the radio frequency detection component is used for detecting the radio frequency pulse signal transmitted by the transmitting coil, and the radio frequency pulse signal detected by the radio frequency detection component is used for feedback control of the radio frequency pulse signal input to the transmitting coil.
2. The radio frequency system according to claim 1, wherein the radio frequency detection component is configured to feed back the detected radio frequency pulse signal to the radio frequency generator or the power amplifier, wherein the radio frequency generator adjusts the power of the radio frequency pulse signal generated by the radio frequency generator based on the radio frequency pulse signal fed back by the radio frequency detection component, or the power amplifier amplifies the radio frequency pulse signal received by the power amplifier from the radio frequency generator based on the radio frequency pulse signal fed back by the radio frequency detection component.
3. The radio frequency system of claim 2, wherein the radio frequency detection component comprises a radio frequency detection antenna disposed between scans in which the magnetic resonance imaging device is disposed and coupled to the transmit coil.
4. The radio frequency system of claim 3, wherein the radio frequency detection antenna is disposed on the magnetic resonance imaging device.
5. The radio frequency system of claim 2, wherein the radio frequency detection component comprises a surface coil for receiving the radio frequency pulse signal transmitted by the transmit coil and feeding the signal back to the radio frequency generator or the power amplifier through a receiver of a magnetic resonance imaging system.
6. The radio frequency system of claim 5, wherein the surface coil receives a radio frequency pulsed signal transmitted by the transmit coil when in a detuned state.
7. A magnetic resonance imaging system comprising a radio frequency system as claimed in any one of claims 1 to 6.
8. A radio frequency control method of magnetic resonance imaging, comprising the steps of:
detecting a radio frequency pulse signal transmitted by a transmitting coil of a magnetic resonance imaging system;
and feedback-controlling the radio-frequency pulse signal input to the transmitting coil based on the detected radio-frequency pulse signal.
9. The radio frequency control method of claim 8, wherein feedback controlling the radio frequency pulse signal input to the transmitting coil based on the detected radio frequency pulse signal comprises:
feeding back the detected radio frequency pulse signal to a radio frequency generator of a magnetic resonance imaging system;
the radio frequency generator adjusts the power of the radio frequency pulse signal generated by the radio frequency generator based on the fed back radio frequency detection signal.
10. The radio frequency control method of claim 8, wherein feedback controlling the radio frequency pulse signal input to the transmitting coil based on the detected radio frequency pulse signal comprises:
feeding back the detected radio frequency pulse signal to a power amplifier of a magnetic resonance imaging system;
the power amplifier amplifies the radio frequency pulse signal received by the power amplifier from the radio frequency generator of the magnetic resonance imaging system based on the fed back radio frequency detection signal.
Technical Field
The invention relates to the field of medical imaging, in particular to a radio frequency system and a radio frequency control method for magnetic resonance imaging and a magnetic resonance imaging system.
Background
Magnetic Resonance Imaging (Magnetic Resonance Imaging) has been widely used in the field of medical diagnosis. The magnetic resonance imaging system forms a static magnetic field using a superconducting magnet, places a scanning object to be imaged in an imaging space of the magnetic resonance imaging system, and aligns proton spins in tissue of the scanning object with a direction of the static magnetic field so as to generate a magnetization vector. Then, a radio frequency field is generated by emitting a radio frequency pulse signal with a certain frequency for excitation. The magnetic resonance phenomenon causes the spin direction of the protons to flip, changing the magnetization vector of the protons. When the spins return the protons to their initial state of magnetization vector in the direction of the static magnetic field after the radio frequency pulse is stopped, a magnetic resonance signal is generated. The magnetic resonance signal is received by the coil and processed by the computer to obtain the image of the scanned object.
In a magnetic resonance imaging system, a radio frequency system is an important component of the magnetic resonance system, and a power amplifier is one of the key technologies of a radio frequency signal link in the magnetic resonance imaging system. Generally the better the fidelity/linearity of the power amplifier, the better the resulting image quality. However, the fidelity/linearity of a power amplifier is a closed-loop control circuit that typically forms the power amplifier by its input signal and its output power feedback signal. In other words, the prior art generally guarantees the fidelity or linearity of the rf pulse signal transmitted to the static magnetic field by guaranteeing the fidelity/linearity of the power amplifier.
However, since the body weight of different subjects is generally different, the load applied to the radio frequency coil is different. As the load changes, the fidelity/linearity of the power amplifier is affected and no longer varies linearly. If the output power of the power amplifier is still used as the feedback signal, the power variation of the whole rf signal chain cannot be truly reflected, and therefore, it is impossible to effectively control the fidelity or linearity of the whole rf signal chain. Furthermore, a typical radio frequency coil consists of many electronic diodes, which also affect the fidelity or linearity of the radio frequency signal link. The existing control method for the fidelity or linearity of the radio frequency signal link does not take these influence factors into consideration.
Therefore, it is desirable to provide a new radio frequency system and a new radio frequency control method for magnetic resonance imaging to solve at least one of the above technical problems.
Disclosure of Invention
The invention aims to provide a radio frequency system and a radio frequency control method for magnetic resonance imaging, and a magnetic resonance imaging system.
An exemplary embodiment of the present invention provides a radio frequency system for magnetic resonance imaging, which includes a radio frequency generator, a power amplifier, a transmit coil, and a radio frequency detection component. The radio frequency generator is used for generating a radio frequency pulse signal. The power amplifier is used for amplifying the radio frequency pulse signal and outputting the amplified radio frequency pulse signal. The transmitting coil is used for receiving the amplified radio frequency pulse signal to transmit the radio frequency pulse signal to a detection object. The radio frequency detection component is used for detecting the radio frequency pulse signal transmitted by the transmitting coil. The radio frequency pulse signal detected by the radio frequency detection component is used for feedback control of the radio frequency pulse signal input to the transmitting coil.
An exemplary embodiment of the present invention also provides a radio frequency control method of magnetic resonance imaging, which includes the steps of: detecting a radio frequency pulse signal transmitted by a transmitting coil of a magnetic resonance imaging system; and feedback-controlling the radio-frequency pulse signal input to the transmitting coil based on the detected radio-frequency pulse signal.
Exemplary embodiments of the present invention also provide a magnetic resonance imaging system comprising the above radio frequency system.
Other features and aspects will become apparent from the following detailed description, the accompanying drawings, and the claims.
Drawings
The invention may be better understood by describing exemplary embodiments thereof in conjunction with the following drawings, in which:
figure 1 is a schematic block diagram of a magnetic resonance imaging system of one embodiment of the invention;
figure 2 is a schematic block diagram of the radio frequency system and receiver connection of a magnetic resonance imaging system according to an embodiment of the present invention;
figure 3 is a schematic block diagram of the radio frequency system and receiver connection of a magnetic resonance imaging system according to another embodiment of the present invention;
figure 4 is a schematic block diagram of the radio frequency system and receiver connection of a magnetic resonance imaging system according to another embodiment of the present invention;
figure 5 is a schematic block diagram of the radio frequency system and receiver connection of a magnetic resonance imaging system according to another embodiment of the present invention;
FIG. 6 is a flow chart of a RF control method for MRI according to an embodiment of the present invention;
fig. 7 is a schematic flow chart of the rf pulse signal input to the transmitting coil based on the detected rf pulse signal feedback control of the rf control method for magnetic resonance imaging according to an embodiment of the present invention;
fig. 8 is a flowchart illustrating a radio frequency pulse signal feedback control of the rf pulse signal input to the transmitting coil based on the detected rf pulse signal in the rf control method for magnetic resonance imaging according to another embodiment of the present invention.
Detailed Description
While specific embodiments of the invention will be described below, it should be noted that in the course of the detailed description of these embodiments, in order to provide a concise and concise description, all features of an actual implementation may not be described in detail. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions are made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another.
Unless otherwise defined, technical or scientific terms used in the claims and the specification should have the ordinary meaning as understood by those of ordinary skill in the art to which the invention belongs. The use of the words "a" or "an" and the like in the description and claims of the present patent application do not denote a limitation of quantity, but rather denote the presence of at least one. The word "comprise" or "comprises", and the like, means that the element or item listed before "comprises" or "comprising" covers the element or item listed after "comprising" or "comprises" and its equivalent, and does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, nor are they restricted to direct or indirect connections. "coupled" may include various means of magnetic coupling, electrical coupling, electromagnetic coupling, and the like.
Figure 1 shows a schematic block diagram of a magnetic resonance imaging system according to an embodiment of the invention. As shown in fig. 1, the magnetic resonance imaging system 10 includes a
The
The gradient system 12 may include gradient coils 121, 122, 123 and a gradient controller 124 respectively arranged in different directions (e.g., up-down, left-right, front-back directions of a human body, a Z-axis, an X-axis, and a Y-axis corresponding to reconstructed coordinates). The gradient controller 124 is used to transmit gradient pulses to the gradient coils 121, 122, 123 to linearly superimpose gradient fields on the static magnetic field to achieve spatial localization of the magnetic resonance signals so that a magnetic resonance image of any slice or volume is produced.
The control system 13 is configured to generate a pulse control sequence, which is sent to the
Fig. 2 is a block diagram of a connection between a radio frequency system and a receiver of a magnetic resonance imaging system according to an embodiment of the invention. The
The transmitting
The
The
The transmit
The transmit
The radio frequency detection component may be configured to detect a radio frequency pulse signal transmitted to the test object when the transmit
In one embodiment of the present invention, the radio frequency detection component includes a radio frequency detection antenna 21 that is electromagnetically coupled to the
In some embodiments of the present invention, the radio frequency detection antenna 21 may be disposed on the magnetic resonance imaging device disposed in the scanning room 100, or may be disposed on a wall of the scanning room 100, or may be disposed on other devices or other locations in the scanning room 100. Generally, in order to better detect and receive the rf pulse signals transmitted from the transmitting
In particular, the radio frequency detection antenna 21 may be disposed at a different location of the magnetic resonance imaging device, for example, the radio frequency detection antenna 21 may be disposed on a housing of the main magnet 14 of the magnetic resonance imaging device, or the radio frequency detection antenna 21 may be disposed on a housing of the transmitting
The rf detection antenna 21 may be connected to the
The detected and received rf pulse signal is fed back to the
Furthermore, by setting the radio frequency detection antenna 21 to form a closed-loop control circuit from the radio frequency pulse signal generation end to the radio frequency pulse signal transmission end, the radio frequency pulse signal actually transmitted to the static magnetic field of the magnetic resonance imaging system can be used as a feedback control signal, so as to adjust the gain or phase of the magnetic resonance imaging radio frequency pulse signal chain. In other words, the radio frequency system 20 of the present invention can improve the fidelity of the whole radio frequency signal chain from the radio frequency pulse signal generating end to the radio frequency pulse signal transmitting end in the magnetic resonance imaging. Therefore, the scanning image quality of the magnetic resonance imaging system can be improved.
Fig. 3 is a schematic block diagram of a connection between a radio frequency system and a receiver of a magnetic resonance imaging system according to another embodiment of the present invention. The
The transmit
The transmit
Since the composition, structure and operation principle of the
The
The detected and received rf pulse signal is fed back to the
The
Fig. 4 is a schematic block diagram of a connection between a radio frequency system and a receiver of a magnetic resonance imaging system according to another embodiment of the present invention. The
The transmit
The structure, composition and operation principle of the
The
The
Further, when the transmit
The
Further, the rf pulse signal actually transmitted to the static magnetic field of the mri system by the transmitting
In addition, the invention directly receives the radio frequency pulse signal transmitted to the static magnetic field by the transmitting
Fig. 5 is a schematic block diagram of the connection between the radio frequency system and the receiver of the magnetic resonance imaging system according to another embodiment of the present invention. The radio frequency system 51 shown in fig. 5 is substantially the same in composition and structure as the radio frequency system shown in fig. 4. The radio frequency system 51 also comprises a
The transmit
The structure, composition and operation principle of the rf system 51 shown in fig. 5 are similar to those of the rf system shown in fig. 4, and are not described herein again.
The radio frequency system shown in fig. 5 is different from the radio frequency system shown in fig. 4 in that the
The
The
Further, the rf pulse signal actually transmitted to the static magnetic field of the magnetic resonance imaging system is transmitted to the
The radio frequency system detects and receives the radio frequency pulse signal transmitted to a detection object by the transmitting coil of the radio frequency system through the radio frequency detecting antenna or the surface coil, and feeds the received radio frequency pulse signal back to the radio frequency generator or the power amplifier to be used as a feedback control signal, so that closed-loop control is performed. The radio frequency system can improve the fidelity of the whole radio frequency signal chain of the magnetic resonance imaging system, thereby improving the scanning image quality of the magnetic resonance imaging system.
In addition, the radio frequency system of the invention utilizes the existing radio frequency signal chain to form closed-loop control from the sending end of the radio frequency pulse signal to the sending end of the radio frequency pulse signal, thereby saving a large number of components and correspondingly saving the occupied space of the magnetic resonance imaging system. Moreover, the radio frequency system of the invention has simple design, and the manufacturing cost of the magnetic resonance imaging system is reduced by arranging the radio frequency detection antenna or utilizing the existing surface coil to detect and receive the radio frequency pulse signal transmitted by the transmitting coil. In addition, by transmitting the radio frequency pulse signal actually transmitted to the static magnetic field to the radio frequency generator or the power amplifier as a feedback control signal, power adjustment can be performed dynamically according to the conditions of the changing body weight of the scanning object, the loss of the radio frequency pulse signal link, and the like, a pulse signal satisfying the establishment of the radio frequency field can be generated better, and the radio frequency signal link can be compensated appropriately to satisfy the requirement of the establishment of the radio frequency field.
Referring also to fig. 1, a magnetic resonance imaging system 10 of the present invention includes the rf system of the above-mentioned embodiment. The magnetic resonance imaging system 10 of the embodiment of the present invention can well control the fidelity of the radio frequency signal chain because it uses the radio frequency system with the above-mentioned features. The magnetic resonance imaging system 10 of the present invention can be better dynamically adjusted according to the changing weight of the detected object, the loss of the radio frequency pulse signal link, etc., can better generate the pulse signal satisfying the establishment of the radio frequency field, and properly compensate the radio frequency signal link to satisfy the requirement of the establishment of the radio frequency field. Thus, the magnetic resonance imaging system 10 of the present invention can improve the quality of the scanned image, resulting in an image with a better signal-to-noise ratio.
Referring to fig. 6, a flow chart of a method 60 for rf control in mri according to an embodiment of the present invention is shown. As shown in fig. 6, the rf control method 60 includes the following steps:
in step 61, radio frequency pulse signals transmitted by a transmit coil of a magnetic resonance imaging system are detected. In one embodiment of the invention, in step 61, the radio frequency pulse signal transmitted by the transmit coil of the magnetic resonance imaging system may be detected by a radio frequency detection component electromagnetically coupled to the transmit coil of the radio frequency system. The radio frequency detection means may comprise a radio frequency detection antenna or a surface coil. In step 61, the configuration, connection relationship, setting position, working principle, etc. of the rf detecting antenna are similar to those of the rf detecting antenna of the rf system discussed above in the present invention, and are not described herein again. The surface coil is similar to the surface coil of the rf system discussed above in terms of structure, connection relationship, installation position, operation principle, etc., and will not be described herein again.
In
Referring to fig. 6 and 7, in one embodiment of the present invention, step 62: the feedback control of the radio frequency pulse signal input to the transmitting coil based on the detected radio frequency pulse signal further comprises the steps of:
in
in
In
In
Further, the radio frequency control method of the present invention may feed back the received radio frequency pulse signal to the radio frequency generator through a radio frequency detection antenna or a surface coil electromagnetically coupled to the transmitting coil, so that a closed loop control circuit from the radio frequency generator to the transmitting coil may be formed. Therefore, the radio frequency control method of the invention can dynamically adjust the power of the radio frequency pulse signal generated by the radio frequency generator according to the received radio frequency detection signal fed back by the radio frequency generator, namely, the transmission power of the radio frequency generator can be dynamically adjusted according to the weight of the detected object to be scanned and the actually received radio frequency pulse signal, so that the radio frequency pulse signal input to the transmission coil has proper power.
Referring now to fig. 6 in conjunction with fig. 8, in another embodiment of the present invention, step 72: the feedback control of the rf pulse signal input to the transmitting coil based on the detected rf pulse signal may further include the steps of:
feeding back the detected radio frequency pulse signal to a power amplifier of a magnetic resonance imaging system in step 721;
in step 722, the power amplifier amplifies the rf pulse signal received by the power amplifier from the rf generator of the mri system based on the fed back rf detection signal.
In step 721, in an embodiment of the present invention, the rf pulse signal transmitted by the transmitting coil may be detected by an rf detecting antenna directly connected to the power amplifier, and the rf detecting antenna feeds the detected rf pulse signal back to the power amplifier of the magnetic resonance imaging system. In another embodiment of the invention, the radio frequency pulse signal transmitted by the transmitting coil may be detected by a surface coil, which feeds back the detected radio frequency pulse signal to a power amplifier of the magnetic resonance imaging system through a receiver of the magnetic resonance imaging system.
In step 722, the power amplifier may amplify the received rf pulse signal from the rf generator of the mri system based on the rf detection signal fed back from the rf detection antenna or the surface coil, so that the rf pulse signal input to the transmitting coil has a proper power.
Further, the radio frequency control method of the present invention may detect the radio frequency pulse signal transmitted by the transmitting coil through the radio frequency detecting antenna or the surface coil, and feed back the detected and received radio frequency pulse signal to the power amplifier of the magnetic resonance imaging system, thereby forming a closed loop control circuit from the power amplifier to the transmitting coil. The closed-loop control circuit can feed back the radio frequency pulse signal actually transmitted by the transmitting coil to the power amplifier, so that the power amplifier can amplify the received radio frequency pulse signal based on the fed-back radio frequency detection signal, the fidelity of a radio frequency signal chain of the magnetic resonance imaging system can be improved, and the scanning image quality of the magnetic resonance imaging system can be improved.
The radio frequency control method of the magnetic resonance imaging detects the radio frequency pulse signal transmitted to the detection object by the transmitting coil through the radio frequency detection antenna or the surface coil, and feeds back the received radio frequency pulse signal to the radio frequency generator or the power amplifier of the radio frequency system to be used as a feedback control signal. Therefore, a closed power control circuit of the magnetic resonance imaging system radio frequency signal chain can be formed, and the fidelity of the magnetic resonance imaging radio frequency signal chain can be better controlled. The radio frequency control method of the magnetic resonance imaging can dynamically adjust the power according to the conditions of the change weight of the detected object, the loss of a radio frequency pulse signal link and the like, can better generate a pulse signal meeting the requirement of establishing a radio frequency field, and properly compensates a radio frequency signal chain so as to meet the requirement of establishing the radio frequency field. Therefore, the radio frequency control method of the magnetic resonance imaging can improve the quality of the scanned image and generate an image with better signal-to-noise ratio.
Some exemplary embodiments have been described above, however, it should be understood that various modifications may be made. For example, suitable results may be achieved if the described techniques are performed in a different order and/or if components in the described systems, architectures, devices, or circuits are combined in a different manner and/or replaced or supplemented by additional components or their equivalents. Accordingly, other embodiments are within the scope of the following claims.
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