CN113848520A

CN113848520A - Ultralow field magnetic resonance imaging system

Info

Publication number: CN113848520A
Application number: CN202111145970.7A
Authority: CN
Inventors: 刘懿龙; 朱瑞星
Original assignee: Hangzhou Weiying Medical Technology Co ltd
Current assignee: Hangzhou Weiying Medical Technology Co ltd
Priority date: 2021-09-28
Filing date: 2021-09-28
Publication date: 2021-12-28

Abstract

The application relates to the technical field of medical equipment, and discloses an ultralow field magnetic resonance imaging system, which comprises: the magnetic device comprises at least four magnetic conductive stand columns, an upper magnetic body rack, an upper magnetic body assembly, a lower magnetic body rack and a lower magnetic body assembly; at least four magnetic conductive upright posts are fixed between the upper magnet frame and the lower magnet frame; the upper magnet assembly is arranged at the lower part of the upper magnet frame; the lower magnet assembly is arranged at the upper part of the lower magnet frame and is opposite to the upper magnet assembly; an accommodating space for accommodating the radio frequency device is formed between the upper magnet assembly and the lower magnet assembly, and at least one channel for communicating the accommodating space with the outside is formed between the at least four magnetic conductive stand columns; an electrical device electrically connects the upper magnet assembly, the lower magnet assembly, the radio frequency device, and the induction device. The ultralow-field magnetic resonance imaging system is good in openness and can be used for scanning multiple parts.

Description

Ultralow field magnetic resonance imaging system

Technical Field

The application relates to the technical field of medical equipment, in particular to an ultralow-field magnetic resonance imaging system.

Background

Magnetic Resonance Imaging (MRI) system is an essential medical device for image diagnosis, and can provide clear images of human tissues.

According to the intensity of the magnetic field, the magnetic resonance imaging system in clinical application can be divided into high field (more than 1T), middle field (0.3-1T), low field (0.1-0.3T) and ultra-low field (less than 0.1T). Generally, whether a superconducting magnet, electromagnet, or permanent magnet is used, the higher the field strength, the heavier and more expensive the system.

Conventional MRI systems require large magnets and associated electronics that generate uniform magnetic fields (B0), including magnet rooms, equipment rooms, operator rooms, etc., which are large in size, costly, and powerful. Meanwhile, in order to isolate the MRI system from the interference of an external electromagnetic field, a closed MRI radio frequency shielding space needs to be constructed, so that strict electromagnetic shielding is realized.

Disclosure of Invention

In order to solve the technical problems that a shielding room is required to be specially built in a magnetic resonance imaging system during magnetic resonance imaging, the system is large in size and high in cost, the embodiment of the application provides an ultra-low field magnetic resonance imaging system, which comprises an open type magnet device, an electric device, a radio frequency device and an induction device, wherein the magnet device comprises at least four magnetic conductive stand columns, an upper magnet frame, an upper magnet assembly, a lower magnet frame and a lower magnet assembly;

the upper magnet frame and the lower magnet frame are arranged in parallel, and the distance between the upper magnet frame and the lower magnet frame is matched with the length of the magnetic conductive upright post;

the at least four magnetic conductive upright posts are fixed between the upper magnet frame and the lower magnet frame;

the upper magnet assembly is arranged at the lower part of the upper magnet frame;

the lower magnet assembly is arranged at the upper part of the lower magnet frame and is opposite to the upper magnet assembly;

an accommodating space for accommodating the radio frequency device is formed between the upper magnet assembly and the lower magnet assembly, and at least one channel for communicating the accommodating space with the outside is formed between the at least four magnetic conductive stand columns;

a gradient magnetic field is formed between the upper magnet assembly and the lower magnet assembly;

the electrical device electrically connects the upper magnet assembly, the lower magnet assembly, the radio frequency device, and the induction device;

the radio frequency device is used for transmitting a radio frequency field required by magnetic resonance imaging and acquiring a radio frequency signal comprising scanning data of an object to be scanned; when magnetic resonance imaging is required, the part to be scanned of the object to be scanned is positioned in the radio frequency field;

the induction device is used for inducing electromagnetic interference signals in the environment.

Optionally, the radio frequency device includes an outer shell, an inner shell, and a transmitting/receiving coil, a cavity is formed between the outer shell and the inner shell, and the transmitting/receiving coil is accommodated in the cavity;

the transmitting/receiving coil is electrically connected with the electrical device; the transmitting/receiving coil is used for transmitting the radio frequency field and collecting the radio frequency signal.

Optionally, the electrical device includes an electrical cabinet, and a microcomputer, a spectrometer, a gradient amplifier, a transmitting radio frequency amplifier, and a receiving radio frequency amplifier, which are disposed inside the electrical cabinet;

the spectrometer is connected with the microcomputer;

the first ends of the gradient amplifier, the transmitting radio frequency amplifier and the receiving radio frequency amplifier are respectively connected with the spectrometer;

the spectrometer is used for:

generating a gradient signal, amplifying the gradient signal and then sending the gradient signal to the gradient amplifier;

generating a radio frequency signal, amplifying the radio frequency signal and then sending the radio frequency signal to the transmitting radio frequency amplifier;

the second end of the gradient amplifier is electrically connected with the upper magnet assembly and the lower magnet assembly so as to amplify the power of the gradient signal generated by the spectrometer and send the amplified gradient signal to the upper magnet assembly and the lower magnet assembly to form the gradient magnetic field;

the second end of the transmitting radio frequency amplifier is electrically connected with the radio frequency device so as to amplify the power of the radio frequency signal generated by the spectrometer and send the radio frequency signal to the radio frequency device to form the radio frequency field;

the second end of the receiving radio frequency amplifier is electrically connected with the radio frequency device so as to receive the radio frequency signal from the radio frequency device and generate and send the amplified radio frequency signal of the radio frequency device to the spectrometer;

the second end of the receiving radio frequency amplifier is also electrically connected with the induction device so as to receive the electromagnetic interference signal from the induction device and generate and send the amplified electromagnetic interference signal to the spectrometer.

Optionally, the electrical apparatus further includes a power module, the power module is disposed inside the electrical cabinet, and the power module is electrically connected to the microcomputer, the spectrometer, the gradient amplifier, the transmitting rf amplifier, and the receiving rf amplifier to supply power to the microcomputer, the spectrometer, the gradient amplifier, the transmitting rf amplifier, and the receiving rf amplifier.

Optionally, the power module is at least one of:

the switching power supply inputs 220V alternating current and outputs direct current;

the linear power supply inputs 220V alternating current and outputs direct current;

a battery.

Optionally, the electrical cabinet includes a metal frame structure and a metal plate, the metal plate is provided with a mesh, and the metal plate is mounted outside the metal frame structure.

Optionally, the induction device includes an induction coil housing and an induction coil, and the induction coil is wound inside the induction coil housing; or the induction device is an electrode which is attached to the surface of the skin of the human body and used for inducing electromagnetic interference signals;

the induction coil or the electrode is electrically connected with the electric device, and the induction coil or the electrode is used for inducing the electromagnetic interference signal.

Optionally, the sensing device is disposed inside the electrical device or in the accommodating space, and the sensing device has different orientations to sense electromagnetic interference signals from various sources inside the electrical device or in the environment.

Optionally, the ultra-low field magnetic resonance imaging system further includes a wireless communication device fixed outside the electrical device, and the microcomputer is capable of communicating with the portable device through the wireless communication device.

Optionally, the ultra-low field magnetic resonance imaging system further includes a roller fixed to the bottom of the electrical device.

Optionally, the magnet device further comprises a first coil, a second coil, a third coil, a fourth coil, a fifth coil and a sixth coil, wherein the first coil, the second coil, the third coil, the fourth coil, the fifth coil and the sixth coil are used for counteracting magnetic field disturbance in the environment;

the first coil and the second coil are wound in a square shape, respectively surround the front surface and the rear surface of the magnet device, and are used for forming a magnetic field in a first direction;

the third coil and the fourth coil are wound in a square shape, respectively surround the left surface and the right surface of the magnet device, and are used for forming a magnetic field in a second direction;

the fifth coil and the sixth coil are wound in a circular shape, respectively surround the upper surface and the lower surface of the magnet device, and are used for forming a magnetic field in a third direction;

wherein the first direction, the second direction and the third direction are mutually perpendicular in pairs.

The ultralow field magnetic resonance imaging system that this application embodiment provided, adopt four at least magnetic conduction stands to support between magnet device's last magnetic conduction frame and lower magnetic conduction frame, need not at magnet device outside or between inside deployment shield cover or shielding etc. make the ultralow field magnetic resonance imaging system of this application embodiment open nature good, can effectively reduce the patient because the discomfort that claustrophobia arouses in the scanning process, open design simultaneously, make the ultralow field magnetic resonance imaging system of this application embodiment can be used for the scanning of a plurality of positions such as head, belly, knee.

In addition, because the ultralow field magnetic resonance imaging system does not need strict electromagnetic shielding, namely the ultralow field magnetic resonance imaging system does not need to be placed in a shielding room, the shielding room does not need to be specially built, the installation is simple and convenient, and the cost can be reduced.

Drawings

FIG. 1 illustrates a schematic structural diagram of an ultra-low field magnetic resonance imaging system, according to some embodiments of the present application;

FIG. 2 illustrates a cross-sectional view of a magnet assembly taken along a section parallel to the x-axis in FIG. 1, in accordance with some embodiments of the present application;

FIG. 3 illustrates a perspective view of a magnet apparatus, according to some embodiments of the present application;

FIG. 4 illustrates a perspective view of a radio frequency device, according to some embodiments of the present application;

FIG. 5 illustrates a cross-sectional view of a radio frequency device taken along section A-A' of FIG. 4, in accordance with some embodiments of the present application;

FIG. 6 illustrates a schematic structural view of an electrical device, according to some embodiments of the present application;

FIG. 7 illustrates a schematic structural diagram of an inductive device, according to some embodiments of the present application;

FIG. 8 illustrates a schematic structural diagram of an ultra-low field magnetic resonance imaging system, according to some embodiments of the present application.

Reference numerals:

10-an induction device; 20-a subject device for magnetic resonance imaging;

21-a magnet arrangement; 22-an electrical device; 23-a radio frequency device; 24-a wireless communication device; 25-a connecting means; 26-a roller; 27-scanning the bed;

11-induction coil housing; 12-an induction coil;

231-a housing; 232-inner shell; 233-chamber; 234-transmit/receive coils;

211-a magnetically conductive column; 212 a-upper magnet frame; 213 a-upper magnet; 214 a-upper plate; 215 a-upper anti-vortex disc; 216 a-upper shim ring; 217-upper gradient coil; 212 b-lower magnet frame; 213 b-lower magnet; 214 b-lower plate; 215 b-lower anti-vortex disc; 216 b-lower shim ring; 218-lower gradient coil; 221-an electrical cabinet; 222-a microcomputer; 223-a spectrometer; 224-gradient amplifier; 225-a transmit radio frequency amplifier; 226 — a receive radio frequency amplifier; 227-a receiving radio frequency amplifier; 228-a power supply module; 229-a patch panel;

271-stage; 272-support part.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

To facilitate understanding of the technical solutions of the present application, some technical terms referred to in the present application will now be described.

Magnetic resonance imaging techniques: magnetic resonance imaging techniques can generate medical images in medical or clinical application scenarios for disease diagnosis. Specifically, the magnetic resonance imaging technique can perform image reconstruction using signals generated by the resonance of atomic nuclei in a strong magnetic field, and can generate tomographic images of a cross section, a sagittal plane, a coronal plane, and various inclined planes of a subject such as a human body.

Magnetic resonance imaging system: the magnetic resonance imaging system can be a low-field and ultra-low-field magnetic resonance imaging system, and can also be a medium-field and high-field magnetic resonance imaging system. As an example, magnetic resonance imaging systems in clinical applications can be generally classified by magnetic field strength into high field (above 1T), medium field (0.3-1T), low field (0.1-0.3T), and ultra-low field (below 0.1T).

As mentioned above, the size of the current MRI system is relatively large, and in order to isolate the MRI system from the interference of the external electromagnetic field, a closed MRI radio frequency shielding space needs to be constructed, so that the MRI system needs to be deployed in a specific room or area of a hospital or a research institution, which greatly limits the application scenarios of the MRI system.

In order to solve the above problem, an embodiment of the present application provides a magnetic resonance imaging system, and in particular, the magnetic resonance imaging system in the embodiment of the present application is mainly applied to an ultra-low field magnetic resonance imaging system, and the ultra-low field magnetic resonance imaging system provided in the embodiment of the present application includes a main apparatus for magnetic resonance imaging for obtaining a magnetic resonance signal and an additionally configured induction device for inducing ambient electromagnetic interference. The main body equipment of the magnetic resonance imaging comprises an open type magnet device, an electric device and a radio frequency device. The magnetic body device is used for providing a strong magnetic field required by magnetic resonance imaging and a gradient magnetic field required by spatial coding, the radio frequency device is used for transmitting a radio frequency field required by the magnetic resonance imaging and acquiring a radio frequency signal comprising scanning data of an object to be scanned, and the induction device is an induction coil comprising a plurality of channels and is used for inducing an electromagnetic interference signal in the environment or an electromagnetic interference signal caused by a power device in the magnetic resonance imaging process; the electric device is used for controlling the generation of the strong magnetic field and the gradient magnetic field, receiving the radio frequency signals collected by the radio frequency device and the electromagnetic interference signals induced by the induction device, and reconstructing images of the radio frequency signals according to the radio frequency signals and the electromagnetic interference signals.

Specifically, the magnet device adopts four at least magnetic conduction stands to support between magnet device's last magnetic conduction frame and lower magnetic conduction frame, need not to dispose shield cover or shielding within the magnet device outside or between the house etc. for the open nature of the ultra-low field magnetic resonance imaging system of this application embodiment is good, can effectively reduce the patient because the discomfort that the claustrophobia arouses in the scanning process, open design simultaneously, make the ultra-low field magnetic resonance imaging system of this application embodiment can be used for the scanning of a plurality of positions such as head, belly, knee.

The induction device can be a single-channel or multi-channel coil (such as a phased array coil), and a plurality of coils can be placed at different positions of the ultralow-field magnetic resonance imaging system and can have different orientations, so that the induction device is used for inducing environmental electromagnetic interference from different sources; the sensing device can also be one or more electrodes which can be attached to the surface of human skin to sense electromagnetic interference signals.

In the magnetic resonance imaging process, the ultralow field magnetic resonance imaging system induces interference signals such as environmental electromagnetic interference signals and the like through the induction device, and then during final imaging, the system eliminates artifacts in magnetic resonance imaging according to the induced electromagnetic interference signals, improves the quality of magnetic resonance imaging, and realizes normal operation of the ultralow field magnetic resonance imaging system in an unshielded or partially shielded environment. In addition, as the main equipment of the magnetic resonance imaging does not need strict electromagnetic shielding, namely, the main equipment of the magnetic resonance imaging does not need to be placed in the shielding room, the special shielding room does not need to be built, the installation is simple and convenient, and the cost can be reduced. In addition, the ultra-low field magnetic resonance imaging system provided by the embodiment Of the application can greatly expand the application scenarios Of magnetic resonance imaging, for example, the system can be applied to Point-Of-Care MRI (POC MRI), emergency room (ICU), medical vehicle and ambulance, and other scenarios.

The present application is further described with reference to the following drawings and detailed description, but not intended to be limited by the present application.

Please refer to fig. 1, which is a schematic structural diagram of an ultra-low field magnetic resonance imaging system according to an embodiment of the present disclosure. The ultra-low field magnetic resonance imaging system comprises an induction device 10 and a main body apparatus 20 for magnetic resonance imaging. The subject apparatus 20 for magnetic resonance imaging includes a magnet device 21, an electric device 22, and a radio frequency device 23. The electrical device 22 is configured to control the magnet device 21 to form a variable gradient magnetic field that can be used for spatial encoding, the electrical device 22 is further configured to control the radio frequency device 23 to emit a radio frequency field required for magnetic resonance imaging, and the electrical device 22 performs image reconstruction based on a signal generated by proton (i.e., hydrogen nuclei) resonance in an imaging region fed back by the radio frequency device 23, that is, a radio frequency signal including scan data of an object to be scanned and acquired by the radio frequency device 23, so as to obtain a magnetic resonance image of the object to be scanned. The sensing device 10 is configured to sense an electromagnetic interference signal caused by a power element of an environment and an apparatus, and feed back the sensed electromagnetic interference signal to the electrical device 22, so that the electrical device 22 can eliminate electromagnetic interference in the radio frequency signal according to the received electromagnetic interference signal when or before image reconstruction is performed based on the radio frequency signal. The ultra-low field magnetic resonance imaging system in the embodiment of the application does not need to specially build a shielding room, realizes an open magnetic resonance imaging scheme, and expands the application scene of magnetic resonance imaging.

The embodiment of the application can realize open magnetic resonance imaging because the magnet device adopts at least four magnetic conductive upright posts, and meanwhile, a shielding cover or shielding room is not required to be arranged outside a magnetic field formed by the magnet device, so that discomfort of a patient caused by claustrophobia in the scanning process can be effectively reduced.

Please refer to fig. 2, which is a schematic structural diagram of a magnet device 21 according to an embodiment of the present application. The magnet assembly 21 includes an upper magnet frame 212a, an upper magnet assembly, a lower magnet frame 212b, and at least four magnetically conductive posts 211. The upper magnet frame 212a and the lower magnet frame 212b are arranged in parallel, the distance between the upper magnet frame 212a and the lower magnet frame 212b is matched with the length of the magnetic conductive upright post 211, and at least four magnetic conductive upright posts 211 are fixed between the upper magnet frame 212a and the lower magnet frame 212 b. The upper magnet assembly is disposed at a lower portion of the upper magnet frame 212a, the lower magnet assembly is disposed at an upper portion of the lower magnet frame 212b, and the upper magnet assembly and the lower magnet assembly are disposed opposite to each other. Wherein oppositely disposed means that the two components are oppositely oriented. The magnetically conductive posts 211 may be used to support the magnet frame and magnet assembly and may also provide a magnetically conductive return path for the magnet assembly 21. An accommodating space for accommodating the radio frequency device 23 is formed between the upper magnet assembly and the lower magnet assembly, and at least one channel for communicating the accommodating space with the outside is formed between the at least four magnetic conductive upright posts 211.

For example, when the rf device is used to collect scan data of the head or the neck, at least four magnetic conductive columns 211 form a channel for communicating the accommodating space with the outside.

For another example, when the radio frequency device is used to collect scanning data of a trunk or four limbs, the at least four magnetic conductive columns 211 form two channels communicating the accommodating space with the outside. Since the upper magnet assembly and the lower magnet assembly have the same structure and are arranged in opposite directions only in the magnet device 21, the configuration of the upper magnet assembly will be described below by taking the upper magnet assembly as an example.

In some embodiments, the upper magnet assembly comprises an upper magnet 213a, an upper pole plate 214a, an upper anti-vortex disc 215a, an upper shim ring 216a, an upper gradient coil 217. An upper magnet 213a is arranged at the lower part of the upper magnet frame 212a, an upper pole plate 214a is arranged at the lower part of the upper magnet 213a, an upper anti-vortex disc 215a and an upper shim ring 216a are arranged at the lower part of the upper pole plate 214a, the upper shim ring 216a is wound on the upper anti-vortex disc 215a, an upper gradient coil 217 is arranged at the lower part of the upper anti-vortex disc 215a, and the circumferential surface of the upper gradient coil 217 is connected with the inner wall surface of the upper shim ring 216 a.

It is understood that the above-described upper magnet assembly is merely an example and that other formed upper magnet assemblies are within the scope of the present application.

Similarly, the lower magnet assembly comprises a lower magnet 213b, a lower pole plate 214b, a lower anti-vortex disc 215b, a lower shim ring 216b, a lower gradient coil 218, wherein a gradient magnetic field is formed between an upper gradient coil 217 in the upper magnet assembly and the lower gradient coil 218 in the lower magnet assembly.

In some embodiments, four magnetic conductive columns 211 may be disposed between the upper magnetic conductive frame 212a and the lower magnetic conductive frame 212b, and four magnetic conductive columns 211 are disposed at four corners of the magnetic conductive frame, for example, as shown in fig. 3.

In some embodiments, six magnetic conductive columns 211 are disposed between the upper magnet frame 212a and the lower magnet frame 212b, and a group of three magnetic conductive columns 211 is distributed on two sides of the magnetic conductive frame along the x-axis direction. The two magnetic conductive posts 211 facing in the y-axis direction form the above-mentioned channel therebetween.

It should be noted that, the number and the layout mode of the magnetic conductive columns are not specifically limited, and any layout scheme capable of stably supporting the magnetic conductive stand, the magnet, the polar plate, the anti-vortex disc, the shimming ring and the gradient coil and meeting the use requirements is within the protection scope of the present application.

In the magnet device 21, the upper magnet frame 212a and the lower magnet frame 212b are supported by at least four magnetically conductive columns 211, and the magnet device 21 according to the embodiment of the present invention is more open and lighter in weight than a square (also referred to as an H-shaped) structure or a C-shaped structure.

Among them, the anti-vortex disc (i.e. the upper anti-vortex disc 215a and the lower anti-vortex disc 215a) adopts a plurality of layers of silicon steel sheets, which can reduce the vortex effect caused by the upper gradient coil 217 and the lower gradient coil 218.

In some embodiments, the magnets (i.e., upper magnet 213a and lower magnet 213b) are neodymium iron boron (Nd)₂Fe₁₄B) A material. The neodymium iron boron magnet has extremely high magnetic energy product (BHmax), excellent machining performance and high cost performance, and the neodymium iron boron magnet is adopted, and the coil heating magnet is additionally arranged on the periphery of the neodymium iron boron magnet, so that the magnet can keep a relatively constant temperature, and further, the imaging requirement of the ultra-low field magnetic resonance imaging system can be met.

In some embodiments, the magnet is made of samarium cobalt (SmCo) which is expensive, but has a high magnetic energy product, reliable coercive force and good temperature characteristics, so that the samarium cobalt is suitable for being used as a magnet for magnetic resonance imaging, and due to the good temperature characteristics of the samarium cobalt magnet, the samarium cobalt can meet the requirement of magnetic resonance imaging without using an additional heating coil. And for temperature induced changes causing changes in the magnetic field strength of the magnet assembly 21, as well as ambient magnetic field disturbances, can be corrected by post-processing algorithms.

In some embodiments, the upper gradient coil 217 and the lower gradient coil 218 are of the same structure and are disposed in opposition, and the configuration of the upper gradient coil 217 will be described below by taking the upper gradient coil 217 as an example.

In some embodiments, the upper gradient coil includes a main coil x +, y +, z +, and shielding coils x-, y-, z-, for countering eddy currents, with the wire windings of the main coil and the corresponding shielding coils (e.g., main coil x + and shielding coil x-) being of identical design but with opposite current directions. The main coil x + and the shielding coil x-are used for providing a gradient magnetic field with the gradient direction being the x-axis direction, the main coil y + and the shielding coil y-are used for providing a gradient magnetic field with the gradient direction being the y-axis direction, and the main coil Z + and the shielding coil Z-are used for providing a gradient magnetic field with the gradient direction being the Z-axis direction. In the upper gradient coil 217, a shield coil z-, a shield coil y-, a shield coil x-, a main coil x +, a main coil y +, and a main coil z + are sequentially arranged from top to bottom. The lower gradient coil has the same structure and is not described in detail herein.

The upper gradient coil 217 and the lower gradient coil 218 may be used for both spatial encoding and first order shimming. The shielding coil in the gradient coil can further effectively reduce the influence of eddy current on imaging, and can improve the image quality of imaging sequences (such as fast spin echo imaging, planar echo imaging, diffusion magnetic resonance imaging and the like) sensitive to the eddy current.

In a further embodiment, a heat dissipation device is disposed between the main coils of the upper gradient coil 217 and the lower gradient coil 218, and since the resistance of the gradient coil is relatively large, the gradient coil generates relatively large joule heat after a large current is applied, and the heat generated may cause the frequency drift of the magnet, the heat dissipation device is employed to dissipate heat from the gradient coil, so that the ultra-low field magnetic resonance imaging system can stably operate. Specifically, the heat dissipation device can be a water-cooled radiator, the water-cooled radiator is adopted for heat exchange, and the heat dissipation effect of the gradient coil is better, so that the ultralow-field magnetic resonance imaging system is more stable.

In some embodiments, the magnet assembly 21 further comprises a metal housing with a mesh, substantially grounded, and the metal housing may enclose the magnet frame, the magnet, the pole plate, the anti-eddy current disk, the shim ring, the upper gradient coil or the lower gradient coil, and the magnetically conductive column, thereby reducing the influence of electromagnetic interference signals in the external environment on the mri scan.

Referring to fig. 3, which is a schematic structural diagram of the magnet apparatus provided in the embodiment of the present application, the magnet apparatus 21 further includes three pairs of coils, i.e., a first coil x1 and a second coil x2, a third coil y1 and a fourth coil y2, a fifth coil z1 and a sixth coil z2, the three pairs of coils surround the magnet frame 212 and the magnetic conductive column 211, e.g., the first coil x1 and the second coil x2 surround the front and rear surfaces of the magnet apparatus in fig. 3, and are wound in a square shape to form a magnetic field in a first direction, i.e., an x direction; the third coil y1 and the fourth coil y2 surround the left and right sides of the magnet device and are wound in a square shape for forming a magnetic field in a second direction, namely the y direction; the fifth coil z1 and the sixth coil z2 are wound in a circular shape around both upper and lower surfaces of the magnet assembly to form a magnetic field in a third direction, i.e., the z direction. The front and the back surfaces can be understood as two surfaces which are sequentially distributed along the x-axis direction, the left and the right surfaces can be understood as two surfaces which are sequentially distributed along the y-axis direction, and the lower and the upper surfaces can be understood as two surfaces which are sequentially distributed along the z-axis direction.

The three pairs of coils can be used to cancel magnetic field disturbances in the environment, for example, low frequency magnetic field disturbances caused by nearby rail traffic (subway, train, etc.), or high power equipment, power transformation equipment, power supply cables, nearby running motor vehicles, etc. Based on this, the arrangement of three pairs of coils can expand the application range of the ultra-low field magnetic resonance imaging system.

In addition to using the three pairs of coils described above to cancel magnetic field perturbations in the environment, in some embodiments, signal processing algorithms may also be used to cancel the effects of magnetic field perturbations on magnetic resonance imaging, particularly gradient echo imaging.

In the embodiment of the present application, the magnet (i.e., the upper magnet 213a and the lower magnet 213b) of the magnet device 21 is used as an active material to form a magnetic field, and the magnet frame (i.e., the upper magnet frame 212a and the lower magnet frame 212b) and the magnetic conductive pillar 211 are used as a passive material to form a magnetic conductive loop, so that the magnetic lines of force of the magnet device 21 are less divergent, the range of 5 gauss lines is reduced, and the influence of the magnetic field on the surrounding environment can be reduced as much as possible. The magnet assembly 21 is more stable without losing openness compared to the conventional C-Shape structure, and has greatly improved openness compared to the H-Shape structure.

Referring to fig. 4 and 5, in the embodiment of the present invention, the rf device 23 is disposed in the gradient magnetic field formed by the magnet device 21, the rf device 23 includes an outer shell 231, an inner shell 232, a cavity 233 formed between the outer shell 231 and the inner shell 232, and a transmitting/receiving coil 234 accommodated in the cavity 233, the cavity 233 and the transmitting/receiving coil 234 may be, for example, as shown in fig. 5, and the space inside the inner shell 232 is an imaging region of the ultra-low field magnetic resonance imaging system. Wherein the imaging area of the rf device 23 communicates with the channel formed by the magnetically conductive post 211 as described above.

It is understood that the coil used for imaging in this application (i.e., the transmit/receive coil 234) is a coil that integrates receiving and transmitting, the transmit/receive coil 234 can transmit radio frequency signals and receive magnetic resonance signals, and the ultra-low field magnetic resonance imaging system switches the operating mode (transmit/receive) of the coil through the electrical device 22. And the receiving and transmitting integrated coil is used, so that the signal to noise ratio of the image is improved. Meanwhile, the receiving and transmitting integrated coil is used, so that the space can be effectively saved, and the comfort level of a patient can be improved.

The transmit/receive coil 234 may comprise a plurality of transmit/receive integrated imaging coil channels, which can simultaneously satisfy the parallel transmission and parallel reception of a plurality of imaging coil channels. Specifically, for different imaging sites, the transmit/receive coil 234 may be configured and wound in different shapes and different winding manners, such as a knee rf device for imaging examination of knee joint shown in fig. 4, a rf device for examination of other sites, such as a head rf device for head examination, a hand rf device for wrist examination, etc., which may be similar in structure, size, and winding manner to the knee rf device. The ultra-low field magnetic resonance imaging system can be matched with transmitting/receiving coils with various shapes and winding wires and is respectively used for checking the head, the wrist, the trunk and the like.

Further, a cooling device may be further disposed in the cavity 233 of the rf device 23, and the rf device 23 may reduce the resistance of the transmitting/receiving coil 234 to the greatest extent by the cooling device, so as to reduce the influence of thermal noise on the imaging of the ultra-low field magnetic resonance imaging system.

Please refer to fig. 6, which is a schematic structural diagram of the electrical device 22 according to an embodiment of the present disclosure. The electrical apparatus 22 comprises an electrical cabinet 221, and a microcomputer 222, a spectrometer 223, a gradient amplifier 224, a transmitting radio frequency amplifier 225 and a receiving radio frequency amplifier provided inside the electrical cabinet 221.

The spectrometer 223 is connected to the microcomputer 2122, the first ends of the gradient amplifier 224, the transmission rf amplifier 225 and the reception rf amplifier are respectively connected to the spectrometer 223, the second end of the gradient amplifier 224 is electrically connected to the magnet device 21 to transmit signals to the magnet device 21, the second end of the transmission rf amplifier 225 is electrically connected to the rf device 23 to transmit rf signals to the rf device 23, the second end of the reception rf amplifier is electrically connected to the rf device 23 to receive signals from the rf device 23, and the second end of the reception rf amplifier is further electrically connected to the sensing device to receive electromagnetic interference signals from the sensing device 10. Specifically, a second end of the gradient amplifier 224 is electrically connected to the gradient coils (i.e., the upper gradient coil 217 and the lower gradient coil 218) to transmit power-amplified gradient signals to the gradient coils; a second end of the transmission rf amplifier 225 is electrically connected to the transmission/reception coil 234 to transmit the power-amplified rf signal to the transmission/reception coil 234; the second terminal of the receiving RF amplifier is electrically connected to the transmitting/receiving coil 234 for receiving the RF signal sensed by the transmitting/receiving coil 234, or the second terminal of the receiving RF amplifier is electrically connected to the sensing coil 12 for receiving the EMI signal sensed by the sensing coil 12.

Communication between the spectrometer 223 and the microcomputer 222 may be accomplished through a network connection. And the signal transmission of the spectrometer, the transmitting radio frequency amplifier, the receiving radio frequency amplifier and the gradient amplifier is realized through coaxial cables.

In some embodiments, the electrical device 22 includes a receiving rf amplifier, and the transmitting/receiving coil 234 and the induction coil 12 are connected to the receiving rf amplifier, so that the rf signal sensed by the transmitting/receiving coil 234 and the emi signal sensed by the induction coil 12 can be transmitted to the same receiving rf amplifier.

In some embodiments, the electrical device 22 includes two receiving rf amplifiers, such as the receiving rf amplifier 226 and the receiving rf amplifier 227 of fig. 6, the transmitting/receiving coil 234 and the induction coil 12 are connected to different receiving rf amplifiers, such as the receiving rf amplifier 226 shown in fig. 8 is connected to the transmitting/receiving coil 234 for receiving the rf signals sensed by the transmitting/receiving coil 234, and the receiving rf amplifier 227 is connected to the induction coil 12 for receiving the emi signals sensed by the induction coil 12.

It should be noted that, in practical use, the microcomputer 222 can communicate with a portable device (such as a notebook computer, a tablet computer, a mobile phone, etc.) so as to control data acquisition and transmission by using the portable device, and transmit images to the portable device for display for disease diagnosis.

In some embodiments, the connection between the portable device and the microcomputer may be accessed under the same local area network to enable communication. The microcomputer can be accessed to a local area network through contact connection, for example, the connection is performed through a network cable (which can be a twisted pair, a coaxial cable, an optical fiber and the like), so that the transmission of signals is completed; the microcomputer can also complete the signal transmission through a non-contact connection, for example, a wireless connection such as Wi-Fi and Bluetooth. The portable device may also access the local area network in the manner described above.

In some embodiments, a microcomputer may also be utilized to provide a Wi-Fi hotspot to which a portable device connects to enable communications.

The electrical cabinet 221 is used to house the main control unit (e.g., microcomputer 222, spectrometer 223), as well as the main power elements (e.g., gradient amplifier 224, transmit radio frequency amplifier 225, receive radio frequency amplifier 226, receive radio frequency amplifier 227, etc.); the electrical cabinet 221 can also support a magnet arrangement fixed above it.

In some embodiments, the electrical cabinet 221 may be comprised of a metal frame structure and a mesh-equipped metal plate mounted on the frame structure. The metal frame structure is used for supporting each element and the magnet frame in the electric cabinet, and the metal plate with meshes can meet the electromagnetic shielding requirement of the power element in the electric cabinet 221 and the heat dissipation requirement of the control unit and the power element in the electric cabinet. The electrical cabinet 221 composed of the metal plate may be a rectangular parallelepiped, a cube, or an irregular shape, and the shape of the electrical cabinet 221 is not limited in this application.

Further, an air cooling or water cooling device is further disposed inside the electrical cabinet 221. The air-cooling or water-cooling device is electrically connected to the microcomputer 222, and the microcomputer 222 can control the opening and closing of the air-cooling or water-cooling device to meet the heat dissipation requirement inside the electrical cabinet 221.

Still further, a temperature sensor may be disposed inside the electrical cabinet 221, and the temperature sensor may be disposed at a critical position inside the electrical cabinet, for example, the temperature sensor is disposed near the power element and the control unit, so as to detect the temperature information inside the electrical cabinet 22 and feed the temperature information back to the microcomputer 222. Based on this, the microcomputer 222 can process the temperature information to obtain the temperature at the position corresponding to the temperature sensor, and adjust the power of the air cooling or water cooling device according to the temperature to adjust the temperature inside the electrical cabinet. The temperature sensor is arranged, so that the temperature inside the electric cabinet can be monitored in real time, meanwhile, the accurate control of the temperature inside the electric cabinet can be realized according to the power of the air cooling or water cooling device for temperature regulation, and the normal work of the control unit and the power element is guaranteed.

In some embodiments, the electrical cabinet 221 further comprises a power module 228 inside, connecting the microcomputer 222, the spectrometer 223, the gradient amplifier 224, the transmitting rf amplifier 225, the receiving rf amplifier 226, the receiving rf amplifier 227, the power module 228 powering the control unit and the power elements.

Further, the power module 228 may be a switch power supply or a linear power supply with an input of 220V ac and an output of dc, that is, an external power supply is connected through a plug of the power supply, and the power module 228 may also be a battery, which directly supplies power to the control unit and the power element.

In some embodiments, the electrical device 22 further includes a connection panel 229, the magnet device 21 and the radio frequency device 23 are connected to power components inside the electrical cabinet 221 through the connection panel, or the magnet device 21 and the radio frequency device 23 are connected to a signal receiving port of an external electronic device through the connection panel 229, wherein the electronic device may be, for example, a mobile phone, a tablet, a computer, or the like, and further, the external electronic device may monitor the radio frequency signal and/or the gradient signal in the ultra-low field magnetic resonance imaging system through the connection panel 229.

In some embodiments, as shown in fig. 1, the main body apparatus 20 for magnetic resonance imaging further includes a scanning table 27, the scanning table 27 includes a stage 271 and a support 272, a first side of the stage 271 is connected to the support 272, and a second side of the stage 271 opposite to the first side is used for placing the object to be scanned. When the scanning bed 27 is connected to the electrical device and the ultra-low field magnetic resonance imaging system starts to perform magnetic resonance imaging, a part of the object stage 271 is located in the imaging area of the radio frequency device 23, so as to perform magnetic resonance imaging on the part to be scanned of the object to be scanned on the object stage 271.

Further, the stage 271 and the supporting portion 272 may be fixedly connected; the stage 271 and the support 272 may be detachably connected, and the stage 271 may be replaced according to the shape and weight of the object to be scanned.

In some embodiments, the radio frequency device 23 may also be fixed to the scanning bed 27, wherein the radio frequency device 23 fixed to the scanning bed 27 may be, for example, a knee radio frequency device for imaging examination of a knee joint.

Referring to fig. 7, which is a schematic structural diagram of an induction device 10 according to an embodiment of the present disclosure, the induction device 10 includes an induction coil housing 11 and an induction coil 12, the induction coil 12 is disposed inside the induction coil housing 11, wound inside the housing, and fixed to any position of a main body 20 of magnetic resonance imaging through the induction coil housing 11; or the sensing device is an electrode attached to the skin surface of the human body to sense the electromagnetic interference signal, and the electrode is electrically connected to the electrical device 22.

In some embodiments, the space formed inside the induction coil housing 11 may be just capable of accommodating the induction coil 12; in some embodiments, the space formed by the induction coil housing 11 may be larger than the induction coil 12, the induction coil may be fixed at any position inside the induction coil housing 11, and further, other components, such as a heat sink, may be integrated inside the induction coil housing 11. A low-noise amplifier module can be further installed inside the induction coil shell to primarily amplify the induced environmental electromagnetic interference.

It should be noted that the induction coil housing 11 may have a shape shown in fig. 7, and may also have a rectangular parallelepiped, a square, a cylinder, and the like, and the shape of the induction coil housing 11 is not limited to the shape shown in fig. 7, and may be designed according to a specific application scenario or a position that needs to be fixed.

In some embodiments, a portion of the sensing device 10 may be fixed near the region to be imaged for sensing the electromagnetic interference in the environment during the imaging process of the radio frequency device 23, so as to eliminate the influence of the electromagnetic interference in the external environment on the magnetic resonance imaging.

Further, the sensing devices 10 fixed near the region to be imaged can have different orientations, and thus the sensing devices 10 can accurately sense electromagnetic interference from various complex sources.

In some embodiments, a portion of the induction device 10 may be fixed inside the electrical cabinet 221, and the induction coil 12 is connected to the corresponding receiving rf amplifier 227 for inducing the electromagnetic interference caused by the power components inside the electrical cabinet 221, so that the induction device 10 may directly induce the electromagnetic interference caused by the power components near the internal power components without being shielded and attenuated by the electrical cabinet 221.

Further, the sensing devices 10 fixed inside the electrical cabinet 221 may have different orientations, so that the sensing devices 10 can accurately sense electromagnetic interference from various complex sources.

In some embodiments, a portion of the sensing device 10 can be fixed inside the stage 271 and/or the supporting portion 271 for sensing the electromagnetic interference in the environment of the system during the imaging process, so as to eliminate the influence of the electromagnetic interference in the external environment on the magnetic resonance imaging.

Further, the sensing device 10 fixed inside the stage 271 and/or the supporting portion 271 may have different orientations, so that the sensing device 10 can accurately sense electromagnetic interference from various sources.

Further, an appropriate algorithm, such as an interference cancellation method disclosed in CN113180636A, CN113176528A or CN113203969A, may be selected to process the signals collected by the induction coil and the transmitting/receiving coil, so as to cancel the electromagnetic interference in the signals collected by the transmitting/receiving coil.

In some embodiments, the subject apparatus 20 for magnetic resonance imaging of the present application may further include a wireless communication device 24, the wireless communication device 24 is fixed outside the electrical cabinet 221 of the electrical device 22, and is connected to the SMA interface of the microcomputer 222 through the connection panel 229, and the wireless communication device 24 may be used for communicating with a portable apparatus, so that the portable apparatus may be used to control the scanning process and to view the examination result. The portable equipment comprises a notebook computer, a tablet computer, a mobile phone and the like.

In some embodiments, the subject apparatus 20 for magnetic resonance imaging of the present application may further include a connection device 25, and the electrical device 22 and the scanning bed 27 are detachably connected through the connection device 25; the connecting device 25 can be used for guiding and locking the process of connecting the scanning bed with the electric device, and can also be used for electrically connecting the radio frequency device and the induction device which are arranged on the scanning bed with the electric device.

In some embodiments, the connection device 25 includes a guiding structure and a locking structure; the guide structure specifically includes: a guide block and a guide rod; a guide groove is arranged on the guide block; a plurality of cam bearing followers are arranged on two sides of the guide rod.

The guide groove is arranged on the electric device 22, the guide rod is arranged on the scanning bed 27, or the guide groove is arranged on the scanning bed 27, and the guide rod is arranged on the electric device 22; the locking structure is used for positioning the guide rod after the guide rod enters the preset position of the guide groove, so that the guide rod is locked in the guide groove.

In some embodiments, the subject mri apparatus 20 of the present application may further include a plurality of rollers 26, and the plurality of rollers 26 are mounted at the bottom of the electrical cabinet 221 by a fixing device.

In some embodiments, the subject apparatus 20 for magnetic resonance imaging of the present application may further include a plurality of rollers 26, and the plurality of rollers 26 are fixed to a side of the supporting portion 272 of the scanning bed 27 away from the stage 271 by a fixing device.

The movement of the subject apparatus 20 for magnetic resonance imaging according to the embodiment of the present application can be facilitated by the rollers 26.

Referring to fig. 8, a schematic receiving diagram of an ultra-low field magnetic resonance imaging system according to an embodiment of the present application is shown, and the working principle of the embodiment of the present application is described below with reference to fig. 8:

the microcomputer 222 is used to issue instructions to the spectrometer 223 under the control of the operator to trigger the spectrometer 223 to generate the waveforms of the gradient signals and the waveforms of the radio frequency signals according to the instructions. After the gradient signals generated by the spectrometer 223 are amplified by the gradient amplifier 224, a gradient magnetic field is formed by the upper gradient coil 217 and the lower gradient coil 218, so that spatial encoding of magnetic resonance signals (in particular, magnetic resonance imaging signals) is realized. In particular, spatial encoding is used to spatially localize the magnetic resonance signals, i.e. to distinguish the location of the source of the magnetic resonance signals. The radio frequency signals generated by the spectrometer 223 are power amplified by the transmission radio frequency amplifier 225, sent to the transmission/reception coil 234, and transmitted by the transmission/reception coil 234 (when the transmission/reception coil 234 is in a transmission mode), so as to excite protons (hydrogen nuclei) in the imaging region. The excited protons may emit radio frequency signals, the radio frequency signals may be received by the transmitting/receiving coil 234 (at this time, the transmitting/receiving coil 234 is in a receiving mode), the transmitting/receiving coil 234 receives the radio frequency signals and then sends the radio frequency signals to the receiving radio frequency amplifier 226, the radio frequency signals are amplified by the receiving radio frequency amplifier 226, then converted into digital signals by the spectrometer 223, and further sent to the microcomputer 222 for processing, the induction coil 12 is used for inducing electromagnetic interference signals in the environment and/or power components, and after power amplification by the receiving radio frequency amplifier 227, converted into digital signals by the spectrometer 223 and sent to the microcomputer 222 for processing. The microcomputer 222 eliminates electromagnetic interference during imaging according to the digital signals received by the receiving rf amplifier 226 and the receiving rf amplifier 227, and obtains and displays an image of a portion to be scanned. Furthermore, the magnet may also be any suitable type of magnet capable of generating a main magnetic field.

The ultra-low field magnetic resonance imaging system provided by the embodiment of the application is provided with the induction device 10 and is matched with a corresponding signal processing algorithm, so that the main body equipment 20 of magnetic resonance imaging is not required to be used between shields, open magnetic resonance imaging is realized, the installation is simple and convenient, the cost can be greatly reduced, and the application scene of magnetic resonance imaging can be greatly expanded.

The above description is only a preferred embodiment of the present application and is not intended to limit the scope of the present application, and it should be understood that all modifications and obvious variations of the present application, which are made by the present specification and drawings, should be considered as included in the present application.

Claims

1. An ultra-low field magnetic resonance imaging system is characterized by comprising an open type magnet device, an electric device, a radio frequency device and an induction device, wherein the magnet device comprises at least four magnetic conductive upright posts, an upper magnet frame, an upper magnet assembly, a lower magnet frame and a lower magnet assembly;

2. The ultra-low field magnetic resonance imaging system of claim 1, wherein the radio frequency device comprises an outer housing, an inner housing, and a transmit/receive coil, a cavity being formed between the outer housing and the inner housing, the transmit/receive coil being received within the cavity;

3. The ultra-low field magnetic resonance imaging system of claim 1, wherein the electrical device comprises an electrical cabinet, and a microcomputer, a spectrometer, a gradient amplifier, a transmit radio frequency amplifier, and a receive radio frequency amplifier disposed inside the electrical cabinet;

the spectrometer is connected with the microcomputer;

the first ends of the gradient amplifier, the transmitting radio frequency amplifier and the receiving radio frequency amplifier are respectively connected with the spectrometer,

the spectrometer is used for:

the second end of the receiving radio frequency amplifier is electrically connected with the radio frequency device so as to receive and amplify the radio frequency signal from the radio frequency device and generate and send the amplified radio frequency signal of the radio frequency device to the spectrometer;

the second end of the receiving radio frequency amplifier is also electrically connected with the induction device so as to receive and amplify the electromagnetic interference signal from the induction device and send the amplified electromagnetic interference signal to the spectrometer.

4. The ultra-low field magnetic resonance imaging system of claim 3, wherein the electrical device further comprises a power module disposed inside the electrical cabinet, the power module electrically connecting the microcomputer, the spectrometer, the gradient amplifier, the transmit radio frequency amplifier, and the receive radio frequency amplifier to power the microcomputer, the spectrometer, the gradient amplifier, the transmit radio frequency amplifier, and the receive radio frequency amplifier.

5. The ultra-low field magnetic resonance imaging system of claim 4, wherein the power module is at least one of:

a battery.

6. The ultra-low field magnetic resonance imaging system of claim 3, wherein the electrical cabinet comprises a metal frame structure and a metal plate, wherein the metal plate is perforated with meshes, and the metal plate is mounted outside the metal frame structure.

7. The ultra-low field magnetic resonance imaging system of claim 1, wherein the induction device comprises an induction coil housing and an induction coil, the induction coil being wound inside the induction coil housing; or the induction device is an electrode which is attached to the surface of the skin of the human body and used for inducing electromagnetic interference signals;

8. The ultra-low field magnetic resonance imaging system of claim 1, wherein the induction device is disposed inside the electrical device or in the receiving space, the induction device having different orientations to induce electromagnetic interference signals from multiple sources inside the electrical device or in the environment.

9. The ultra-low field magnetic resonance imaging system of claim 3, further comprising a wireless communication device secured to the exterior of the electrical device, the microcomputer being capable of communicating with a portable device through the wireless communication device.

10. The ultra-low field magnetic resonance imaging system of claim 1, further comprising a roller fixed to a bottom of the electrical device.

11. The ultra-low field magnetic resonance imaging system of claim 1, wherein the magnet arrangement further comprises first, second, third, fourth, fifth and sixth coils for counteracting magnetic field disturbances in the environment;