Monitoring method and device for magnetic resonance imaging system and magnetic resonance imaging system

Abstract

The present invention provides a monitoring method and device for a magnetic resonance imaging system and a magnetic resonance imaging system. The monitoring method includes obtaining the specific absorption rate of the whole body of the object to be detected, obtaining the ratio between the specific absorption rate of a local region of the object to be detected and the specific absorption rate of the whole body based on the parameter information of the current local coupling coil in the magnetic resonance imaging system, and calculating the specific absorption rate of the local region of the object to be detected based on the ratio between the specific absorption rate of the local region and the specific absorption rate of the whole body and the specific absorption rate of the whole body.

Description

Technical Field

[0001] The present invention relates to medical imaging technology, and more particularly to a monitoring method and device for a magnetic resonance imaging system and a magnetic resonance imaging system. Background Art

[0002] Magnetic resonance imaging (MRI), as a medical imaging modality, can obtain images of the human body without using X-rays or other ionizing radiation. MRI uses a magnet with a strong magnetic field to generate a static magnetic field B0. When the part of the human body to be imaged is positioned in the static magnetic field B0, the nuclear spins associated with the hydrogen nuclei in the human tissue generate polarization, so that the tissue of the part to be imaged generates a longitudinal magnetization vector macroscopically. When a radiofrequency field B1 intersecting the direction of the static magnetic field B0 is applied, the direction of proton rotation changes, so that the tissue of the part to be imaged generates a transverse magnetization vector macroscopically. After removing the radiofrequency field B1, the transverse magnetization vector decays in a spiral shape until it returns to zero, and a free induction decay signal is generated during the decay process. This free induction decay signal can be collected as a magnetic resonance signal, and the tissue image of the part to be imaged can be reconstructed based on the collected signal. The gradient system is used to emit slice selection gradient pulses, phase encoding gradient pulses, and frequency encoding gradient pulses (also called readout gradient pulses) to provide three-dimensional position information for the above magnetic resonance signal to achieve image reconstruction.

[0003] In recent years, people have increasingly chosen to implant medical, orthopedic, plastic and other devices in the body. Before using magnetic resonance imaging technology to image the human body, safety assessments need to be made for implants in the human body, such as cardiac pacemakers, orthopedic implant devices, puncture devices, etc., because such implants may cause safety problems during magnetic resonance imaging. When using a body coil as the transmitting and / or receiving coil, since the body coil can transmit or receive signals to the entire body of the detected object and has a large coverage area (or imaging area), the implant will inevitably be exposed in the imaging area, which will cause a large specific absorption rate (SAR) of the detected object and pose a danger to the detected object.

[0004] Generally, local coils can be used for scanning. The body coil and the local coil respectively correspond to two different control circuits (or hardware), that is, components such as a frequency synthesizer and / or a radiofrequency amplifier, which will increase the complexity of the hardware of the magnetic resonance imaging system. However, the specific absorption rate of the local area can be estimated based on the radiofrequency power sent by the radiofrequency amplifier to the local coil. If the control hardware of the local coil is omitted and the electromagnetic coupling between the body coil and the local coil is used to control the local coil to generate a radiofrequency field through the control hardware of the body coil, there will still be some problems. For example, the specific absorption rate of the local area of the detected object cannot be monitored or obtained during this process, and the danger to the detected object cannot be known or controlled. Summary of the Invention

[0005] The present invention provides a monitoring method and apparatus for a magnetic resonance imaging system, and a magnetic resonance imaging system.

[0006] An exemplary embodiment of the present invention provides a monitoring method for a magnetic resonance imaging system. The monitoring method includes obtaining the specific absorption rate of the whole body of a detected object, obtaining the ratio between the specific absorption rate of a local area of the detected object and the specific absorption rate of the whole body based on the parameter information of the current local coupling coil in the magnetic resonance imaging system, and calculating the specific absorption rate of the local area based on the ratio and the specific absorption rate of the whole body.

[0007] Specifically, obtaining the ratio between the specific absorption rate of the local area of the detected object and the specific absorption rate of the whole body based on the parameter information of the current local coupling coil in the magnetic resonance imaging system includes obtaining the parameter information of the current local coupling coil; and obtaining the ratio corresponding to the parameter information of the current local coupling coil based on a pre-determined correspondence between the parameter information and the ratio.

[0008] Specifically, the correspondence is pre-determined by electromagnetic simulation.

[0009] Specifically, the parameter information of the local coupling coil includes the size of the local coupling coil.

[0010] Specifically, the parameter information of the local coupling coil includes the position information of the local coupling coil in the magnetic resonance imaging system.

[0011] Specifically, the position information of the local coupling coil in the magnetic resonance imaging system is obtained based on the center of the region of interest in the pre-scan image.

[0012] Specifically, the position information of the local coupling coil in the magnetic resonance imaging system is obtained based on the switch signal triggered when the local coupling coil is installed at different positions on the scanning bedplate.

[0013] Specifically, before obtaining the ratio between the specific absorption rate of the local area and the specific absorption rate of the whole body, it further includes determining whether there is an implant in the detected object. When there is an implant in the detected object, the user is prompted to install the local coupling coil on the scanning bedplate.

[0014] Specifically, before obtaining the ratio between the specific absorption rate of the local area and the specific absorption rate of the whole body, it further includes determining whether the local coupling coil is installed on the scanning bedplate. If the local coupling coil is installed on the scanning panel, the ratio between the specific absorption rate of the local area of the detected object and the specific absorption rate of the whole body is obtained.

[0015] Specifically, determining whether the local coupling coil is installed on the scanning bedplate includes determining whether the local coupling coil is installed based on the magnitude of the radio frequency power required to complete the scan.

[0016] Specifically, determining whether the local coupling coil is installed on the scanning bedplate includes determining whether the local coupling coil is installed based on the switch signal triggered by the installation of the local coupling coil on the scanning bedplate.

[0017] Specifically, the monitoring method further includes displaying the specific absorption rate of the local area and the specific absorption rate of the whole body.

[0018] An exemplary embodiment of the present invention also provides a non-transitory computer-readable storage medium for storing a computer program, which when executed by a computer causes the computer to execute the above-mentioned monitoring method.

[0019] An exemplary embodiment of the present invention also provides a monitoring device for a magnetic resonance imaging system. The monitoring device includes an acquisition module and a calculation module. The acquisition module is used to acquire the specific absorption rate of the whole body of the object to be detected, and based on the parameter information of the current local coupling coil in the magnetic resonance imaging system, acquire the ratio between the specific absorption rate of the local area and the specific absorption rate of the whole body of the object to be detected. The calculation module is used to calculate the specific absorption rate of the local area based on the ratio and the specific absorption rate of the whole body.

[0020] Specifically, the acquisition module is further used to acquire the parameter information of the current local coupling coil, and based on the pre-determined correspondence between the parameter information and the ratio, acquire the ratio corresponding to the parameter information of the current local coupling coil.

[0021] Specifically, the parameter information of the local coupling coil includes the size of the local coupling coil.

[0022] Specifically, the parameter information of the local coupling coil includes the position information of the local coupling coil in the magnetic resonance imaging system.

[0023] Specifically, the monitoring device further includes a first judgment module for judging whether there is an implant in the object to be detected, and when there is an implant in the object to be detected, prompting the user to install the local coupling coil on the scanning bedplate.

[0024] Specifically, the monitoring device further includes a second judgment module for judging whether the local coupling coil is installed on the scanning bedplate. If the local coupling coil is installed on the scanning panel, the ratio between the specific absorption rate of the local area and the specific absorption rate of the whole body of the object to be detected is acquired.

[0025] Specifically, the monitoring device further includes a display module for displaying the specific absorption rate of the local area and the specific absorption rate of the whole body.

[0026] An exemplary embodiment of the present invention also provides a magnetic resonance imaging system, which includes a local coupling coil and the monitoring device as described above.

[0027] Specifically, the local coupling coil is used to concentrate the radio frequency field generated by the body coil in a local area within the imaging space.

[0028] Other features and aspects will become clear through the following detailed description, drawings, and claims. Description of the Drawings

[0029] The present invention can be better understood by describing exemplary embodiments of the present invention in conjunction with the drawings. In the drawings:

[0030] Figure 1 is a schematic diagram of a magnetic resonance imaging system according to some embodiments of the present invention;

[0031] Figure 2 is according to Figure 1 a local schematic diagram in the magnetic resonance imaging system shown;

[0032] Figure 3 is a schematic diagram of a monitoring device according to some embodiments of the present invention;

[0033] Figure 4 is a flowchart of a monitoring method according to some embodiments of the present invention;

[0034] Figure 5 is a flowchart of a monitoring method according to some other embodiments of the present invention; and

[0035] Figure 6 is a flowchart of a monitoring method according to still some other embodiments of the present invention. Detailed Embodiments

[0036] Specific embodiments of the present invention will be described below. It should be noted that in the specific description of these embodiments, for the sake of concise description, it is impossible for this specification to describe all features of the actual embodiments in detail. It should be understood that in the actual implementation of any embodiment, just as in the process of any engineering project or design project, in order to achieve the specific goals of the developer and to meet system-related or business-related restrictions, various specific decisions are often made, and these will also change from one embodiment to another. In addition, it should also be understood that although the efforts made in this development process may be complex and lengthy, for those of ordinary skill in the art related to the content disclosed in the present invention, some design, manufacturing, or production changes based on the technical content disclosed in this disclosure are only conventional technical means and should not be understood as the content of this disclosure being insufficient.

[0037] Unless otherwise defined, technical terms or scientific terms used in the claims and the specification shall have the ordinary meaning as understood by those of ordinary skill in the technical field to which the present invention pertains. The terms "first", "second", and similar terms used in the description of the present invention patent application and the claims do not denote any order, quantity, or importance, but are only used to distinguish different components. The terms "a" or "an" and similar terms do not denote a quantity limitation, but mean that there is at least one. The terms "comprising" or "including" and similar terms mean that the elements or items appearing before "comprising" or "including" cover the elements or items listed after "comprising" or "including" and their equivalent elements, and do not exclude other elements or items. The terms "connected" or "coupled" and similar terms are not limited to physical or mechanical connections, nor are they limited to direct or indirect connections.

[0038] Figure 1 A schematic diagram of an MRI system 100 according to some embodiments of the present invention is shown. As Figure 1 shown, the MRI system 100 includes a scanner 110, a controller unit 120, and a data processing unit 130. The above MRI system 100 is only described as an example. In other embodiments, the MRI system 100 may have various transformation forms as long as it can collect image data from the object to be detected.

[0039] Scanner 110 can be used to acquire data of the object to be detected 116. The controller unit 120 is coupled to the scanner 110 to control the operation of the scanner 110. The scanner 110 may include a main magnet 111, a radio frequency (RF) transmit coil 112, a frequency synthesizer 101, an RF amplifier 103, a transmit / receive switch (T / R switch) 105, a gradient coil system 117, a gradient coil driver 118, and an RF receive coil 119.

[0040] The main magnet 111 generally includes, for example, a toroidal superconducting magnet, which is installed in a toroidal vacuum vessel. The toroidal superconducting magnet defines a cylindrical space surrounding the object to be detected 116. A constant static magnetic field, such as the static magnetic field B0, is generated along the Z direction of the cylindrical space. The MRI system 100 uses the formed static magnetic field B0 to transmit a static magnetic pulse signal to the object to be detected 116 placed in the imaging space, so that the precession of the protons in the object to be detected 116 becomes orderly, generating a longitudinal magnetization vector.

[0041] The frequency synthesizer 101 is used to generate RF pulses. The RF pulses may include RF excitation pulses, which are amplified by the RF amplifier 103 and then applied to the RF transmit coil 112 through the T / R switch 105, so that the RF transmit coil 112 emits an RF magnetic field B1 orthogonal to the static magnetic field B0 to the object to be detected 116 to excite the atomic nuclei in the object to be detected 116, and the longitudinal magnetization vector is converted into a transverse magnetization vector. When the RF excitation pulse ends, a free induction decay signal is generated during the process that the transverse magnetization vector of the object to be detected 116 gradually returns to zero, that is, the magnetic resonance signal that can be collected.

[0042] Specifically, in a magnetic resonance imaging system, a body coil can be used as a transmit coil or a receive coil. That is to say, an RF field can be emitted through the body coil and a magnetic resonance signal can be received through the body coil (the first mode); of course, a local coil can also be used as both a transmit coil and a receive coil, that is, an RF field is emitted through the local coil and a magnetic resonance signal is received through the local coil (the second mode); in addition, the most commonly used mode is to emit an RF field through the body coil and receive a magnetic resonance signal through the local coil (the third mode). In the second and third modes, additional control hardware is required to control the local coil, and the image quality obtained in the first mode is poor.

[0043] Therefore, based on the electromagnetic coupling between the body coil and the local coil, the function of the local coil emitting an RF field and collecting a magnetic resonance signal can be realized only through the control hardware of the body coil. In some embodiments, the local coil includes a head coil, a joint coil, and the like.

[0044] The gradient coil system 117 forms a magnetic field gradient in the imaging space to provide three-dimensional position information for the above-mentioned magnetic resonance signals. The magnetic resonance signals can be received by the radio frequency receiving coil 119 or the body coil or local coil in the receiving mode, and the data processing unit 130 can process the received magnetic resonance signals to obtain the required images or image data.

[0045] Specifically, the gradient coil system 117 may include three gradient coils. Each of the three gradient coils generates a gradient magnetic field tilted into one of three mutually perpendicular spatial axes (e.g., the X-axis, Y-axis, and Z-axis), and generates a gradient field in each of the slice selection direction, phase encoding direction, and frequency encoding direction according to the imaging conditions. More specifically, the gradient coil system 117 applies a gradient field in the slice selection direction of the object 116 to be detected to select a slice; and the radio frequency transmitting coil 112 emits a radio frequency excitation pulse to the selected slice of the object 116 to be detected and excites the slice. The gradient coil system 117 also applies a gradient field in the phase encoding direction of the object 116 to be detected to phase-encode the magnetic resonance signals of the excited slice. Subsequently, the gradient coil system 117 applies a gradient field in the frequency encoding direction of the object 116 to be detected to frequency-encode the magnetic resonance signals of the excited slice.

[0046] The gradient coil driver 118 is used to provide appropriate power signals for the above three gradient coils respectively in response to the sequence control signals issued by the controller unit 120.

[0047] The scanner 110 may also include a data acquisition unit 114, which is used to acquire the magnetic resonance signals received by the radio frequency surface coil 119 or the body coil. The data acquisition unit 114 may include, for example, a radio frequency preamplifier (not shown), a phase detector (not shown), and an analog / digital converter (not shown). The radio frequency preamplifier is used to amplify the magnetic resonance signals received by the radio frequency surface coil 119 or the body coil, the phase detector is used to perform phase detection on the amplified magnetic resonance signals, and the analog / digital converter is used to convert the phase-detected magnetic resonance signals from analog signals to digital signals. The above-mentioned digitized magnetic resonance signals can be processed by the data processing unit 130 through operations, reconstructions, etc. to obtain medical images.

[0048] The data processing unit 130 may include a computer and a storage medium, on which a program for performing predetermined data processing to be executed by the computer is recorded. The data processing unit 130 can be connected to the controller unit 120 and perform data processing based on the control signals received from the controller unit 120. The data processing unit 130 can also be connected to the data acquisition unit 114 to receive the magnetic resonance signals output by the data acquisition unit 114 for performing the above-mentioned data processing.

[0049] The controller unit 120 may include a computer and a storage medium for storing a program executable by the computer. When the computer executes the program, it may cause multiple components of the scanner 110 to perform operations corresponding to the above imaging sequence. It may also cause the data processing unit 130 to perform predetermined data processing.

[0050] The storage media of the controller unit 120 and the data processing unit 130 may include, for example, ROM, floppy disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, or non-volatile memory cards.

[0051] The controller unit 120 may be set up and / or arranged to be used in different ways. For example, in some implementations, a single controller unit 120 may be used; in other implementations, multiple controller units 120 are configured to work together (e.g., based on a distributed processing configuration) or individually, with each controller unit 120 configured to handle a specific aspect and / or function, and / or process data for generating models only for a specific medical imaging system 100. In some implementations, the controller unit 120 may be local (e.g., co-located with one or more medical imaging systems 100, such as within the same facility and / or the same local network); in other implementations, the controller unit 120 may be remote and thus can only be accessed via a remote connection (e.g., via the Internet or other available remote access technologies). In a particular implementation, the controller unit 120 may be configured in a cloud-like manner and may be accessed and / or used in a manner substantially similar to the way other cloud-based systems are accessed and used.

[0052] The MRI system 100 further includes a detection bed 140 on which the object to be detected 116 is placed. The object to be detected 116 can be moved into or out of the imaging space by moving the detection bed 140 based on a control signal from the controller unit 120.

[0053] The MRI system 100 further includes an operation console unit 150 connected to the controller unit 120. The operation console unit 150 can send the acquired operation signals to the controller unit 120 to control the operating states of the above-mentioned components of, for example, the detection bed 140 and the scanner 110. The operation signals may include, for example, a scan protocol, parameters, etc. selected manually or automatically. The scan protocol may include the above-mentioned imaging sequence. In addition, the operation console unit 150 can send the acquired operation signals to the controller unit 120 to control the data processing unit 130 in order to obtain a desired image.

[0054] The operation console unit 150 may include a user input device, such as a keyboard, a mouse, a voice-activated controller, or any other suitable input device, etc. The operator can input operation signals / control signals to the controller unit 120 through the user input device.

[0055] The MRI system 100 may further include a display unit 160, which can be connected to the operation console unit 150 to display an operation interface and can also be connected to the data processing unit 130 to display images.

[0056] In some embodiments, the system 100 can be connected to one or more display units, cloud networks, printers, workstations, and / or similar devices located locally or remotely via one or more configurable wired and / or wireless networks, such as the Internet and / or a virtual private network.

[0057] Figure 2 is shown Figure 1 A partial schematic diagram of the shown magnetic resonance imaging system. As Figure 2 shown, the magnetic resonance imaging system includes a body coil 170 and a local coupling coil 180. Among them, the local coupling coil 180 is used to concentrate the radio frequency field generated by the body coil 170 in a local area within the imaging space.

[0058] The local coupling coil 180 can be mounted on the scanning panel and form a coupling with the body coil 170. Specifically, the radio frequency amplifier 103 can amplify the radio frequency excitation pulse (i.e., radio frequency power) and apply it to the body coil 170. The body coil 170 can generate a radio frequency field. The local coupling coil 180 can concentrate the radio frequency field generated by the body coil 170 in the internal imaging area of the local coupling coil 180 based on the electromagnetic coupling effect to achieve the function of a normal local coil without adding or setting up hardware circuits for controlling the local coil, such as control hardware like a radio frequency amplifier.

[0059] In some embodiments, the local coupling coil 180 is a birdcage coil. More specifically, the local coupling coil 180 is a non-plugged birdcage coil. Preferably, the local coupling coil is a birdcage coil without any circuit interface. In some special embodiments, a circuit interface may be reserved or provided on the local coupling coil. The magnetic resonance imaging system can determine whether the local coupling coil is mounted on the scanning panel through this circuit interface. However, the circuit interface is not necessarily reserved or present. When there is no circuit interface on the local coupling coil, other methods can also be used to confirm whether the local coupling coil is mounted on the scanning panel.

[0060] In some embodiments, the magnetic resonance imaging system includes a monitoring device 200. Generally, the monitoring device 200 can estimate the Specific Absorption Rate (SAR) generated when the object to be detected is scanned by acquiring the radio frequency power provided by the radio frequency amplifier 103 to the body coil 170. At this time, the specific absorption rate is the specific absorption rate of the whole body of the object to be detected. The term "specific absorption rate" refers to the power or energy absorbed per unit of the human body, and its unit is W / kg. SAR is a safety-related parameter commonly used in the magnetic resonance imaging process.

[0061] If the body coil 170 is selected as the radio frequency transmitting and / or receiving coil, the monitoring device 200 can acquire the radio frequency power, and by dividing the radio frequency power by the weight of the object to be detected, the specific absorption rate of the whole body can be obtained. When the local coupling coil 180 is installed on the scanning panel and concentrates the radio frequency field, the monitoring device 200 cannot obtain the specific absorption rate of the local area corresponding to the scanning of the local coupling coil. The specific absorption rate of the whole body (whole body SAR) refers to the power and energy absorbed per unit corresponding to the weight of the whole body of the object to be detected. The specific absorption rate of the local area refers to the power and energy absorbed per unit of the body part exposed in the local coupling coil. The specific absorption rate of the local area includes the specific absorption rate of a part of the body (partial body SAR), the specific absorption rate of the head (head SAR), and the local specific absorption rate (local SAR). Among them, the head SAR is a special case of the local body SAR, and the local SAR refers to the specific absorption rate corresponding to a mass of 10 g.

[0062] Therefore, the present invention proposes a monitoring device 300, which can use the parameter information of the local coupling coil to obtain the proportional relationship between the specific absorption rate of the local area and the specific absorption rate of the whole body, and calculate the specific absorption rate of the local area based on the specific absorption rate of the whole body.

[0063] Figure 3 A schematic diagram of the monitoring device 300 according to some embodiments of the present invention is shown. As Figure 3 shown, the monitoring device 300 includes an acquisition module 310 and a calculation module 320. The acquisition module 310 can acquire the specific absorption rate of the whole body of the object to be detected, and based on the parameter information of the local coupling coil in the magnetic resonance imaging system, acquire the ratio r between the specific absorption rate of the local area and the specific absorption rate of the whole body of the object to be detected. The calculation module 320 can calculate the specific absorption rate of the local area based on the ratio r between the specific absorption rate of the local area and the specific absorption rate of the whole body and the specific absorption rate of the whole body.

[0064] The ratio can be either the quotient obtained by dividing the specific absorption rate of a local region by the specific absorption rate of the whole body, or the quotient obtained by dividing the specific absorption rate of the whole body by the specific absorption rate of a local region, or the quotient obtained by performing an operation on the specific absorption rate of a local region or the specific absorption rate of the whole body after an adaptive transformation.

[0065] Specifically, the local coupling coil is used to concentrate the radiofrequency field generated by the body coil in a local region within the imaging space.

[0066] Specifically, the parameter information of the local coupling coil includes the size of the local coupling coil. Specifically, by confirming the size of the local coupling coil, the ratio between the local coupling coil and the body coil can be confirmed, that is, the ratio between the imaging region of the local coupling coil and the imaging region of the body coil.

[0067] Specifically, the parameter information of the local coupling coil includes the position information of the local coupling coil in the magnetic resonance imaging system. Specifically, the position information of the local coupling coil in the magnetic resonance imaging system can be the position of the local coupling coil relative to the body coil or relative to the scanning panel.

[0068] In some embodiments, the acquisition module 310 can obtain the ratio r between the specific absorption rate of the local region of the detected object and the specific absorption rate of the whole body only based on the size of the local coupling coil. Specifically, when the size of the local coupling coil is one-third of the body coil, the ratio r between the specific absorption rate of the local region and the specific absorption rate of the whole body can be roughly estimated to be one-third. Obtaining the ratio only through the size of the local coupling coil can conveniently determine the ratio of the local region SAR to the whole body SAR to obtain the local region SAR.

[0069] In some embodiments, more precisely, the acquisition module 310 can obtain the ratio r between the specific absorption rate of the local region of the detected object and the specific absorption rate of the whole body according to the size of the local coupling coil and the position information of the local coupling coil.

[0070] Specifically, the acquisition module 310 can be further configured to obtain the parameter information of the current local coupling coil, and based on the pre-determined correspondence between the parameter information and the ratio, obtain the ratio corresponding to the parameter information of the current local coupling coil. In some embodiments, the correspondence is pre-determined through electromagnetic simulation.

[0071] Specifically, in electromagnetic simulation, by placing a body coil, a local coupling coil, and a human body model, based on the internal geometries of the body coil and the local coupling coil, changing the position of the local coupling coil relative to the body coil can obtain the electric or magnetic field distribution within the local coupling coil. Based on the electromagnetic constants (e.g., variable conductivity) in the human body model, the correspondence between the ratio and the position of the local coupling coil can be obtained. By placing local coupling coils of different sizes, the correspondence between the ratio and the position under different sizes of local coupling coils can be determined. This correspondence can be stored in a magnetic resonance imaging system, for example, stored in the magnetic resonance imaging system in the form of a look-up table (LUT). During the actual scanning process, based on the parameter information of the local coupling coil obtained, the corresponding ratio can be obtained. Of course, during the electromagnetic simulation process, the maximum value in the correspondence between the ratio and the size and position relationship of the local coupling coil can also be taken, and this maximum value can be used for monitoring during the actual scanning process, which can facilitate and safely monitor the local region SAR.

[0072] In electromagnetic simulation, different correspondences can also be obtained according to the weights of two parameters (size and position information). For example, the position of the local coupling coil can be selected as the dominant factor. The ratio r can be mainly related to the position of the local coupling coil. When it is located at the center of the body coil, the ratio r is a higher value. When it partially exceeds the imaging region of the body coil, the ratio r is a lower value, and the influence of the size of the local coupling coil on the ratio r is smaller. Of course, the choice of weight can be determined by the user or confirmed based on information such as the size, material, and type of the implant.

[0073] In some embodiments, the position information of the local coupling coil in the magnetic resonance imaging system can be obtained based on the switch signals triggered when the local coupling coil is installed at different positions on the scanning bed plate. Different positions on the scanning panel can include multiple switches. When the local coupling coil is installed on the scanning bed plate, a certain switch will be triggered to generate a trigger signal, and the system will obtain the position information corresponding to this switch, which is the current position of the local coupling coil.

[0074] In other embodiments, the position information of the local coupling coil in the magnetic resonance imaging system can also be obtained based on the center of the region of interest in the pre-scan image. The pre-scan image is the initial image obtained during the pre-scan process. The pre-scan usually refers to the scanning process carried out before the formal imaging scan to confirm the scan sequence, etc. The pre-scan usually obtains an initial image corresponding to a relatively large area of the object to be detected. The user can confirm the part or region to be imaged and scanned, that is, the region of interest (ROI), based on this initial image. The center of the region of interest can be roughly considered as the center of the local coupling coil, thus confirming the position of the local coupling coil.

[0075] In still other embodiments, the position information of the local coupling coil relative to the body coil can also be manually input by the user. On the actual scanning bed board, there are scales on some parts of the bed board. By reading the scale of the currently installed local coupling coil, the position of the current local coupling coil is confirmed and input into the system through the operation console unit (such as Figure 1 the component 150 shown), and the position information of the local coupling coil can be obtained.

[0076] Although the present invention lists three embodiments to obtain the position information of the local coupling coil relative to the body coil, those skilled in the art should understand that other suitable methods can also be used to confirm the position of the local coupling coil, and are not limited to the above three.

[0077] The calculation module 320 can calculate the specific absorption rate of the local area based on the ratio r between the specific absorption rate of the local area and the specific absorption rate of the whole body and the specific absorption rate of the whole body. Specifically, the specific absorption rate of the local area is equal to the product of the specific absorption rate of the whole body and the ratio r between the specific absorption rate of the local area and the specific absorption rate of the whole body.

[0078] In some embodiments, the monitoring device 300 further includes a first judgment module 330, which is used to judge whether there is an implant in the detected object. When there is an implant in the detected object, the user is prompted to install a local coupling coil on the scanning bed board.

[0079] If there is no implant in the detected object, a conventional process or scanning sequence is used for scanning to estimate and monitor the specific absorption rate of the whole body of the detected object.

[0080] Specifically, the first judgment module 330 can judge whether the detected object contains an implant by the difference between the images or one-dimensional signals obtained by executing two scanning sequences with different frequency encoding directions, or can also judge whether the detected object contains an implant by the difference between two sets of images obtained by changing the echo time. Those skilled in the art should understand that other suitable methods can also be used to confirm whether there is an implant in the detected object. For example, but not limited to, oral inquiry or case query, etc.

[0081] In some embodiments, the monitoring device 300 further includes a second judgment module 340, which is used to judge whether a local coupling coil is installed on the scanning bed board. If a local coupling coil is installed on the scanning panel, the ratio between the specific absorption rate of the local area of the detected object and the specific absorption rate of the whole body is obtained.

[0082] In some embodiments, the second determination module 340 can determine whether a local coupling coil is installed by judging based on the magnitude of the radio frequency power (transmit power) required to complete the scan. Generally, for a body coil and a local coil, the required radio frequency powers are quite different, perhaps a multiple difference. For example, the radio frequency power required for a body coil may be several thousand, while the radio frequency power required for a local coil may be only a few hundred. Therefore, it is possible to determine whether a local coupling coil is installed or set on the scanning panel by judging the magnitude of the radio frequency power.

[0083] In some other embodiments, the second determination module 340 can also determine whether a local coupling coil is installed based on the switch signal triggered by the installation of the local coupling coil on the scanning bedplate. Specifically, similar to the determination of the position information of the local coupling coil, it is possible to determine whether a local coupling coil is installed by the switch signal triggered on the scanning panel.

[0084] In still some other embodiments, the second determination module 340 can also determine whether a local coupling coil is installed based on the local coupling coil and the circuit interface. Specifically, the local coupling coil in the present invention adopts a non-plugged birdcage coil. However, in certain situations, at least one circuit interface may be reserved in the local coupling coil. When the local coupling coil is installed on the scanning panel, the magnetic resonance imaging system will confirm that the local coupling coil has been installed through the circuit interface. However, those skilled in the art should understand that this embodiment does not limit that a circuit interface must be reserved on the local coupling coil. When there is no circuit interface, other methods can also be used to confirm the position of the local coupling coil.

[0085] Although the present invention lists three embodiments to determine whether a local coupling coil is installed or set on the scanning panel, those skilled in the art should understand that other suitable methods can also be used for determination, for example, by means of manual input by the user.

[0086] In some embodiments, the monitoring device 300 further includes a display module 350, which is used to display the specific absorption rate of the local area and the specific absorption rate of the whole body. Specifically, the display module 350 can also be such as Figure 1 the display unit shown.

[0087] Figure 4 The flowchart of the monitoring method 400 of the magnetic resonance imaging system according to some embodiments of the present invention is shown. As Figure 4 shown, the monitoring method 400 of the magnetic resonance imaging system according to some embodiments of the present invention includes step 410, step 420, and step 430.

[0088] In step 410, the specific absorption rate (SAR) of the whole body of the object to be detected is obtained. Specifically, the SAR of the whole body is estimated and obtained based on the RF power provided by the RF amplifier to the body coil.

[0089] In step 420, based on the parameter information of the local coupling coil in the magnetic resonance imaging system, the ratio between the SAR of the local area of the object to be detected and the SAR of the whole body is obtained.

[0090] Specifically, the local coupling coil is used to concentrate the RF field generated by the body coil in a local area within the imaging space. By setting up a non-powered birdcage-type local coil and providing RF power through the control circuit of the body coil, based on the electromagnetic coupling effect, the RF field of the body coil is concentrated within the imaging area of the local coil. This can not only reduce the hardware requirements for the control circuit of the local coil in the magnetic resonance imaging system, lower the system complexity, but also realize the function of the local coil and reduce the SAR of the local area of the object to be detected.

[0091] In some embodiments, the parameter information of the local coupling coil includes the size of the local coupling coil. In some embodiments, the parameter information of the local coupling coil further includes the position information of the local coupling coil in the magnetic resonance imaging system.

[0092] In some embodiments, the position information of the local coupling coil relative to the body coil is obtained based on the center of the region of interest in the pre-scanned image. In other embodiments, the position information of the local coupling coil relative to the body coil is obtained based on the switch signals triggered when the local coupling coil is installed at different positions on the scanning bedplate.

[0093] In some embodiments, the ratio between the SAR of the local area and the SAR of the whole body may be related only to the size of the local coupling coil. By obtaining the ratio between the sizes of the local coupling coil and the body coil, the ratio between the SAR of the local area and the SAR of the whole body can be roughly estimated.

[0094] In other embodiments, the ratio between the SAR of the local area and the SAR of the whole body may be related only to the position information of the local coupling coil relative to the body coil. By confirming the position of the local coupling coil relative to the body coil, the ratio between the SAR of the local area and the SAR of the whole body can be roughly estimated. In still other embodiments, the ratio between the SAR of the local area and the SAR of the whole body may be related to both the size of the local coupling coil and the position information of the local coupling coil relative to the body coil.

[0095] Specifically, obtaining the ratio between the specific absorption rate of the local region of the object to be detected and the specific absorption rate of the whole body based on the parameter information of the current local coupling coil in the magnetic resonance imaging system includes obtaining the parameter information of the current local coupling coil and obtaining the ratio corresponding to the parameter information of the current local coupling coil based on a pre-determined correspondence between the parameter information and the ratio. Among them, the correspondence is pre-determined through electromagnetic simulation.

[0096] In some embodiments, during the electromagnetic simulation process, based on the body coil, the local coupling coil, and the human body model, the correspondence between the ratio between the specific absorption rate of the local region and the specific absorption rate of the whole body and the size of the local coupling coil and the position information of the local coupling coil relative to the body coil can be obtained. This correspondence can be stored in the magnetic resonance imaging system in the form of, for example, a look-up table. During the actual scanning process, based on the parameter information of the current local coupling coil obtained during the actual scanning process, the ratio corresponding to this parameter information can be obtained.

[0097] In step 430, calculate the specific absorption rate of the local region based on the ratio between the specific absorption rate of the local region and the specific absorption rate of the whole body and the specific absorption rate of the whole body.

[0098] In some embodiments, the specific absorption rate of the local region is equal to the product of the specific absorption rate of the whole body and the ratio between the specific absorption rate of the local region and the specific absorption rate of the whole body.

[0099] In some embodiments, the monitoring method 400 further includes step 440.

[0100] In step 440, display the specific absorption rate of the local region and the specific absorption rate of the whole body.

[0101] Figure 5 The flowchart of the monitoring method 500 of the magnetic resonance imaging system according to some other embodiments of the present invention is shown. As Figure 5 shown, different from the monitoring method 400 shown in Figure 4 the monitoring method 500 of the magnetic resonance imaging system according to some embodiments of the present invention further includes step 550.

[0102] In step 550, determine whether there is an implant in the object to be detected. When it is determined that there is an implant in the object to be detected, go to step 551. When it is determined that there is no implant in the object to be detected, go to step 552.

[0103] In step 551, when there is an implant in the object to be detected, prompt the user to install a local coupling coil on the scanning bed board. Then go to step 410.

[0104] In step 552, the system estimates and displays the specific absorption rate (SAR) of the whole body. Specifically, the SAR of the whole body is estimated based on the RF power provided by the RF amplifier to the body coil.

[0105] Figure 6 The flowchart of the monitoring method 600 of the magnetic resonance imaging system according to some other embodiments of the present invention is shown. As Figure 6 shown, different from the monitoring method 400 shown in Figure 4 , the monitoring method 600 of the magnetic resonance imaging system according to some embodiments of the present invention further includes step 650 and step 660.

[0106] In step 650, it is determined whether there is an implant in the object to be detected. When it is determined that there is an implant in the object to be detected, step 651 is entered; when it is determined that there is no implant in the object to be detected, step 660 is entered.

[0107] In step 651, when there is an implant in the object to be detected, the user is prompted to install a local coupling coil on the scanning bedplate. Then step 660 is entered.

[0108] In step 660, it is determined whether a local coupling coil is installed on the scanning bedplate. If a local coupling coil is installed on the scanning bedplate, step 410 is entered; if a local coupling coil is not installed on the scanning bedplate, step 662 is entered.

[0109] In some embodiments, it can be determined whether a local coupling coil is installed on the scanning panel based on the magnitude of the RF power required to complete the scan. In some other embodiments, it is also determined whether a local coupling coil is installed based on the switch signal triggered by the installation of the local coupling coil on the scanning bedplate.

[0110] In step 662, the system estimates and displays the SAR of the whole body. Specifically, the SAR of the whole body is estimated based on the RF power provided by the RF amplifier to the body coil.

[0111] In summary, for the monitoring method of the magnetic resonance imaging system according to some embodiments of the present invention, on the one hand, the control circuit of the body coil is used to control the body coil to generate an RF field, and based on the non-powered local coupling coil, the RF field is concentrated in the local imaging area, which can not only reduce the complexity of the system in terms of hardware, but also reduce the SAR during system scanning, especially for the object to be detected with implants in the body. On the other hand, based on the parameter information of the local coupling coil, including position information and size information, the ratio of the SAR of the local area to the SAR of the whole body is estimated, and based on the SAR of the whole body estimated by the system, the SAR of the local area can be calculated, and the SAR of the local area can be obtained conveniently and quickly on the premise of omitting the control hardware of the local coil.

[0112] The present invention can also provide a non-transitory computer-readable storage medium for storing an instruction set and / or a computer program, which, when executed by a computer, causes the computer to execute the method for obtaining a truncated partial prediction image described above. The computer executing the instruction set and / or the computer program can be the computer of an MRI system or other devices / modules of the MRI system. In one embodiment, the instruction set and / or the computer program can be programmed in the processor / controller of the computer.

[0113] Specifically, when the instruction set and / or the computer program is executed by a computer, it causes the computer to:

[0114] Obtain the specific absorption rate of the whole body of the object to be detected;

[0115] Based on the parameter information of the local coupling coil in the magnetic resonance imaging system, obtain the ratio between the specific absorption rate of the local area of the object to be detected and the specific absorption rate of the whole body; and

[0116] Based on the ratio and the specific absorption rate of the whole body, calculate the specific absorption rate of the local area.

[0117] The instructions as described above can be combined into one instruction for execution, and any instruction can also be split into multiple instructions for execution. In addition, it is not limited to the execution order of the above instructions.

[0118] As used herein, the term "computer" can include any processor-based or microprocessor-based system, including systems using microcontrollers, reduced instruction set computers (RISC), application-specific integrated circuits (ASIC), logic circuits, and any other circuits or processors capable of performing the functions described herein. The above examples are merely exemplary and are not intended to limit the definition and / or meaning of the term "computer" in any way.

[0119] The instruction set can include various commands that direct a computer or processor acting as a processing unit to perform specific operations, such as the methods and processes of various embodiments. The instruction set can take the form of a software program, which can form part of one or more tangible non-transitory computer-readable media. The software can take various forms, such as system software or application software. In addition, the software can take the form of a collection of independent programs or modules, program modules within a larger program, or a part of a program module. The software can also include modular programming in the form of object-oriented programming. The processing of the input data by the processing unit can be in response to an operator's command, or in response to a previous processing result, or in response to a request made by another processing unit.

[0120] Some exemplary embodiments have been described above. However, it should be understood that various modifications can be made. For example, suitable results can be achieved if the described techniques are performed in a different order and / or if the components in the described system, architecture, device, or circuit are combined in a different manner and / or are replaced or supplemented by other components or their equivalents. Accordingly, other embodiments also fall within the scope of the claims.

Claims

1. A monitoring method for a magnetic resonance imaging system: Obtain the specific absorption rate of the whole body of the object to be detected; Based on the parameter information of the current local coupling coil in the magnetic resonance imaging system, obtain the ratio between the specific absorption rate of the local area of the object to be detected and the specific absorption rate of the whole body, where the local coupling coil is not powered on and is used to concentrate the radio frequency field generated by the body coil in a local area within the imaging space; Based on the ratio and the specific absorption rate of the whole body, calculate the specific absorption rate of the local area of the object to be detected; And Reduce the specific absorption rate of the local area of the object to be detected.

2. The monitoring method according to claim 1, wherein, Based on the parameter information of the current local coupling coil in the magnetic resonance imaging system, obtaining the ratio between the specific absorption rate of the local area of the object to be detected and the specific absorption rate of the whole body includes: Obtain the parameter information of the current local coupling coil; and Based on a pre-determined correspondence between parameter information and ratios, obtain the ratio corresponding to the parameter information of the current local coupling coil.

3. The monitoring method according to claim 2, wherein, The correspondence is pre-determined through electromagnetic simulation.

4. The monitoring method according to claim 1, wherein, The parameter information of the local coupling coil includes the size of the local coupling coil.

5. The monitoring method according to claim 1, wherein The parameter information of the local coupling coil includes the position information of the local coupling coil in the magnetic resonance imaging system.

6. The monitoring method according to claim 5, wherein The position information of the local coupling coil in the magnetic resonance imaging system is obtained based on the center of the region of interest in the pre-scan image.

7. The monitoring method according to claim 5, wherein The position information of the local coupling coil in the magnetic resonance imaging system is obtained based on the switch signal triggered when the local coupling coil is installed at different positions on the scanning bed board.

8. The monitoring method according to claim 1, wherein, Before obtaining the ratio between the specific absorption rate of the local area and the specific absorption rate of the whole body, it further includes: Determine whether there is an implant in the object to be detected. When there is an implant in the object to be detected, prompt the user to install the local coupling coil on the scanning bed board.

9. The monitoring method according to claim 8, wherein, Before obtaining the ratio between the specific absorption rate of the local area and the specific absorption rate of the whole body, it further includes: Determine whether the local coupling coil is installed on the scanning bed board. If the local coupling coil is installed on the scanning panel, obtain the ratio between the specific absorption rate of the local area of the object to be detected and the specific absorption rate of the whole body.

10. The monitoring method according to claim 9, wherein, Determining whether the local coupling coil is installed on the scanning bed board includes determining whether the local coupling coil is installed based on the magnitude of the radio frequency power required to complete the scan.

11. The monitoring method according to claim 9, wherein, Determining whether the local coupling coil is installed on the scanning bed board includes determining whether the local coupling coil is installed based on the switch signal triggered when the local coupling coil is installed on the scanning bed board.

12. The monitoring method according to claim 1, wherein, It further includes: Display the specific absorption rate of the local area and the specific absorption rate of the whole body.

13. A non-transitory computer-readable storage medium for storing a computer program, which when executed by a computer causes the computer to execute the monitoring method of the magnetic resonance imaging system according to any one of claims 1 - 12.

14. A monitoring device for a magnetic resonance imaging system, which includes: An acquisition module, configured to acquire the specific absorption rate of the whole body of the object to be detected, and based on the parameter information of the current local coupling coil in the magnetic resonance imaging system, acquire the ratio between the specific absorption rate of the local area of the object to be detected and the specific absorption rate of the whole body, wherein the local coupling coil is not powered on and is used to concentrate the radio frequency field generated by the body coil in a local area within the imaging space; A calculation module, configured to calculate the specific absorption rate of the local area of the object to be detected based on the ratio and the specific absorption rate of the whole body; And A control circuit, configured to reduce the specific absorption rate of the local area of the object to be detected.

15. The monitoring device according to claim 14, wherein, The acquisition module is further configured to: Acquire the parameter information of the current local coupling coil; and Based on a pre-determined correspondence between parameter information and the ratio, acquire the ratio corresponding to the parameter information of the current local coupling coil.

16. The monitoring device according to claim 14, wherein, The parameter information of the local coupling coil includes the size of the local coupling coil.

17. The monitoring device according to claim 14, wherein, The parameter information of the local coupling coil includes the position information of the local coupling coil in the magnetic resonance imaging system.

18. The monitoring device according to claim 14, wherein, The monitoring device further includes: A first determination module, configured to determine whether there is an implant in the object to be detected, and when there is an implant in the object to be detected, prompt the user to install the local coupling coil on the scanning bedplate.

19. The monitoring device according to claim 18, wherein, The monitoring device further includes: A second determination module, configured to determine whether the local coupling coil is installed on the scanning bedplate, and if the local coupling coil is installed on the scanning panel, acquire the ratio between the specific absorption rate of the local area of the object to be detected and the specific absorption rate of the whole body.

20. The monitoring device according to claim 14, wherein The monitoring device further includes: A display module, configured to display the specific absorption rate of the local area and the specific absorption rate of the whole body.

21. A magnetic resonance imaging system, comprising: A local coupling coil; And The monitoring device according to any one of claims 14-20.

22. The magnetic resonance imaging system according to claim 21, wherein, The local coupling coil is used to concentrate the radio frequency field generated by the body coil in a local area within the imaging space.

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