Portable superconducting magnetic resonance imaging system

Abstract

The invention relates to a portable superconducting magnetic resonance imaging system, which is characterized in that a superconducting magnet adopts a super-shielding electromagnetic design, a 5-gauss line range is compressed to be close to a magnet vacuum container, a superconducting magnet coil supporting structure adopts an integrated design, the mass of the supporting structure is effectively reduced, a superconducting magnet coil is wound by magnesium diboride, and the magnetic resonance imaging effect is improved. Closed-loop operation is achieved through the superconducting joint technology, the superconducting magnet low-temperature system conducts and cools a superconducting magnet coil through a Stirling cryocooler, and additional compressor equipment is not needed. The gradient device adopts an asymmetric stepped design and can accommodate the shoulders of the patient to enter. The horizontal superconducting magnet structure supports the use of a multi-channel parallel emission radio frequency coil. The superconducting magnet, the gradient device, the radio frequency coil and the cabinet are placed on a movable frame, and the frame can pull and hang the examination bed. According to the invention, the portable examination of the super-reach magnetic resonance imaging system is realized.

Description

Technical Field

[0001] The invention belongs to the field of superconducting mechanics, and in particular relates to a portable superconducting magnetic resonance imaging system used for magnetic resonance imaging detection. Background Art

[0002] Magnetic resonance imaging technology is constantly developing, and one of the important directions is portability. Portable MRI makes up for the shortcomings of conventional MRI instruments in specialized application scenarios, such as obstetrics, ICU, vehicle-mounted, and monitoring. The development direction of miniaturization and portability is allowing conventional MRI instruments to break through the walls of radiology and imaging departments and become intelligent bedside equipment. At present, portable MRI instruments have gained market access and played an irreplaceable role in specialized application scenarios. However, the existing portable MRI mainly generates the main magnetic field by permanent magnets, which have low magnetic field strength and poor uniformity, and the magnetic field is easily affected by temperature and drifts. In comparison, superconducting magnets can generate stronger and more uniform magnetic fields, and superconducting constant current operation can ensure extremely high magnetic field stability. Decades ago, the general medical permanent magnetic resonance imaging was updated to superconducting MRI to achieve a significant improvement in key indicators such as magnetic field strength, uniformity, and stability, and the imaging quality was significantly improved, thus gradually developing into the mainstream MRI technology. Referring to the development history of general magnetic resonance imaging technology, superconducting magnets are used to replace permanent magnets, and the portability of superconducting magnets is realized through innovative design concepts. It is expected to lead the technological trend of portable magnetic resonance imaging and greatly expand the scope of market application.

[0003] Chinese invention patent application CN113143245A discloses a mobile magnetic resonance system, including a scanning mechanism, a joint cabinet, a mobile chassis and a bed mechanism. The upper and lower poles of the permanent magnet generate the main magnetic field. Its overall technical method is significantly different from the superconducting magnetic resonance system of the present invention; the US invention patent application US20240361405A1 discloses a portable magnetic resonance device, which adopts a C-shaped permanent magnet structure and is moved by a cylindrical seat at the bottom. At present, most portable magnetic resonance imaging systems are constructed based on permanent magnets. The magnets do not require a low-temperature system and electricity maintenance. The key is to achieve lightweight by reducing the magnetic field and optimizing the iron yoke. Summary of the invention

[0004] Superconducting magnets have significantly improved magnetic field performance compared to permanent magnets, but the use of superconducting magnets in portable magnetic resonance imaging technology faces challenges. The key issue is how to abandon the supporting electrical equipment for maintaining the operation of superconducting magnets, and how to achieve the lightweight of superconducting magnets. To solve the above technical problems, the present invention proposes a portable superconducting magnetic resonance imaging system, which is integrated into a portable magnetic resonance imaging system to achieve the mobility of the superconducting magnet, thereby further achieving the portability of the entire system.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A portable superconducting magnetic resonance imaging system comprises a superconducting magnet, a gradient device, a radio frequency coil, a cabinet, a frame and an examination bed. The superconducting magnet is arranged in a superconducting magnet vacuum cavity, the gradient device is arranged in a warm hole of the superconducting magnet vacuum cavity, the radio frequency coil is arranged in the hole of the gradient coil, the cabinet is arranged at the lower end of the superconducting magnet vacuum cavity and is placed on the frame; the superconducting magnet adopts a Stirling refrigerator for conduction cooling, the gradient device is an asymmetric structure, and the radio frequency coil supports multi-channel parallel transmission; the examination bed is connected to one end of the warm hole of the superconducting magnet vacuum cavity; the superconducting magnet, the gradient device, the radio frequency coil and the cabinet are placed on a movable frame.

[0007] Furthermore, the superconducting magnet comprises four main coils and four shielding coils. The shielding coils are located at the periphery of the main coils and are longer in axial direction than the main coils, thereby providing excellent magnetic field shielding performance.

[0008] Furthermore, the main coil and the shielding coil of the superconducting magnet are wound with magnesium diboride superconducting wires and connected in series with superconducting joints to form a closed loop.

[0009] Furthermore, the main coil and the shielding coil of the superconducting magnet are supported by only one frame without the need for end plates, and are hoisted on the vacuum container at the ends of the frame.

[0010] Furthermore, the vacuum container of the superconducting magnet is in a stepped shape, and the apertures at both ends are larger than the inner aperture.

[0011] Furthermore, the Stirling refrigerator includes two stages of cold heads, namely a primary cold head and a secondary cold head, wherein the primary cold head is fixed on the superconducting magnet cold shield, and the secondary cold head is located inside the superconducting magnet cold shield, and a cooling belt is arranged on the secondary cold head to be connected to the shielding coil and the main coil of the superconducting magnet.

[0012] Furthermore, the gradient device comprises three-axis actively shielded gradient coils, namely, an X gradient coil, a Y gradient coil, and a Z gradient coil, each coil comprising two sub-coils, namely, a main coil and a shielding coil, wherein the conductor of the Z gradient coil is a hollow circular tube structure with cooling water flowing inside.

[0013] Furthermore, with the vertical line of the center of the gradient device axis as a reference, the cylindrical shell where the shielding coil of the gradient coil is located is symmetrical about the vertical line, the cylindrical shell where the main coil of the gradient coil is located is asymmetrical about the vertical line, and the center of the gradient magnetic field homogeneity zone of the gradient coil coincides with the center of the gradient device axis.

[0014] Furthermore, the gradient device is asymmetric about a vertical line at the center of the gradient device axis, and is stepped at one end, with the aperture decreasing from large to small. The larger aperture can accommodate the patient's shoulder, and the patient's head is located at the smaller aperture.

[0015] Furthermore, the gradient device is located in the warm hole of the superconducting magnet, the axis of the vacuum container of the superconducting magnet coincides with the axis of the gradient device, and the centers of the axes coincide.

[0016] Furthermore, the examination bed can be towed on the frame of the superconducting magnet and moved together or detached and moved separately as needed.

[0017] Beneficial effects:

[0018] Although the current portable permanent magnet magnetic resonance imaging system has emerged in the field of rapid disease screening, the demand for improving image quality has always been a research hotspot in this field. The present invention uses magnesium diboride to increase the operating temperature of the superconducting coil, uses its multi-filament structure and superconducting joint technology to achieve closed-loop stable operation, and uses a Stirling refrigerator plus a compact design of a superconducting magnet to achieve the portability of the superconducting magnet, thereby further achieving the portability of the entire system. The portable superconducting magnetic resonance imaging system is significantly superior to the current portable permanent magnet magnetic resonance imaging system in key indicators such as magnetic field strength, uniformity, and stability, and supports the output of high signal-to-noise ratio and high-resolution images, thereby greatly expanding the scope of application of portable magnetic resonance imaging technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the portable superconducting magnetic resonance imaging system of the present invention. In order to show the internal structure, the superconducting magnet and the gradient device are shown in 1 / 2 model;

[0020] Figure 2 A schematic diagram of a superconducting magnet of a portable superconducting magnetic resonance imaging system of the present invention;

[0021] Figure 3 A schematic diagram of a gradient device of a portable superconducting magnetic resonance imaging system of the present invention;

[0022] Figure 4a is a schematic diagram of an X-gradient coil;

[0023] Figure 4b is a schematic diagram of the Y gradient coil;

[0024] Figure 4c Schematic diagram of the Z gradient coil.

[0025] Explanation of the accompanying drawings: 1 is the first superconducting magnet main coil, 2 is the second superconducting magnet main coil, 3 is the third superconducting magnet main coil, 4 is the fourth superconducting magnet main coil, 5 is the first superconducting magnet shielding coil, 6 is the second superconducting magnet shielding coil, 7 is the third superconducting magnet shielding coil, 8 is the fourth superconducting magnet shielding coil, 9 is the superconducting magnet coil skeleton, 10 is the superconducting magnet cold shield, 11 is the superconducting magnet vacuum container, 12 is the Stirling refrigerator, 13 is the gradient device, 13a is the X gradient coil, 13b is the Y gradient coil, 13c is the Z gradient coil, 14 is the radio frequency coil, 15 is the frame, 16 is the examination bed, and 17 is the patient. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] like Figure 1 , Figure 2 As shown, in the portable superconducting magnetic resonance imaging system of the embodiment of the present invention, the superconducting magnet adopts Stirling refrigerator 12 for conduction cooling, and no compressor is needed; the gradient device 13 is an asymmetric structure; it supports the use of multi-channel parallel transmission radio frequency coil 14; the required spectrometer, gradient power amplifier, radio frequency power amplifier, water chiller, and battery are integrated in a cabinet; a movable examination bed 16 is configured; the superconducting magnet, gradient device, radio frequency coil, and cabinet are placed on a movable frame 15, and the frame can tow the examination bed 16. The gradient device 13 is placed in the warm hole of the superconducting magnet vacuum cavity 11, the radio frequency coil 14 is placed in the cavity of the gradient coil 13, the cabinet is placed at the lower end of the superconducting magnet vacuum cavity 11, and is placed on the frame 15, and the examination bed 16 is connected to one end of the warm hole of the superconducting magnet vacuum cavity 11.

[0028] like Figure 2As shown, the superconducting magnet comprises four main coils and four shielding coils. The shielding coils are located at the periphery of the main coils and are longer in axial direction than the main coils, providing excellent magnetic field shielding performance. The main coils are respectively the first superconducting magnet main coil 1, the second superconducting magnet main coil 2, the third superconducting magnet main coil 3, and the fourth superconducting magnet main coil 4. The superconducting magnet main coils are arranged from one end to the other end of the superconducting magnet in the order of the first superconducting magnet main coil 1, the second superconducting magnet main coil 2, the third superconducting magnet main coil 3, and the fourth superconducting magnet main coil 4, wherein the first superconducting magnet main coil 1 and the fourth superconducting magnet main coil 4 are symmetrical about the center plane of the magnet, and the second superconducting magnet main coil 2 and the third superconducting magnet main coil 3 are symmetrical about the center plane of the magnet. The shielding coils are respectively a first superconducting magnet shielding coil 5, a second superconducting magnet shielding coil 6, a third superconducting magnet shielding coil 7, and a fourth superconducting magnet shielding coil 8, wherein the first superconducting magnet shielding coil 5 and the fourth superconducting magnet shielding coil 8 are symmetrical about the center plane of the magnet, and the second superconducting magnet shielding coil 6 and the third superconducting magnet shielding coil 7 are symmetrical about the center plane of the magnet.

[0029] Preferably, the first superconducting magnet shielding coil 5, the second superconducting magnet shielding coil 6, the third superconducting magnet shielding coil 7 and the fourth superconducting magnet shielding coil 8 are respectively located on the periphery of the first superconducting magnet main coil 1, the second superconducting magnet main coil 2, the third superconducting magnet main coil 3 and the fourth superconducting magnet main coil 4, and their axial length is greater than that of the first superconducting magnet main coil 1, the second superconducting magnet main coil 2, the third superconducting magnet main coil 3 and the fourth superconducting magnet main coil 4, providing excellent magnetic field shielding performance.

[0030] Preferably, the main coil and the shielding coil of the superconducting magnet are wound with magnesium diboride superconducting wire and connected in series with superconducting joints to form a closed loop.

[0031] Preferably, the main coil and the shielding coil of the superconducting magnet are supported by only one superconducting magnet coil skeleton 9 without end plates, and are hoisted on the superconducting magnet vacuum container 11 at the ends of the superconducting magnet coil skeleton 9 .

[0032] Preferably, the superconducting magnet vacuum container 11 is in a stepped shape, and the apertures at both ends are larger than the inner aperture.

[0033] Preferably, the Stirling refrigerator 12 used includes two stages of cold heads, namely a primary cold head and a secondary cold head, wherein the primary cold head is fixed on the superconducting magnet cold shield 10, and the secondary cold head is located inside the superconducting magnet cold shield 10, and a cold conductive belt is arranged on the secondary cold head to be connected to the first superconducting magnet shielding coil 5, the second superconducting magnet shielding coil 6, the third superconducting magnet shielding coil 7, the fourth superconducting magnet shielding coil 8 and the main coils, namely the first superconducting magnet main coil 1, the second superconducting magnet main coil 2, the third superconducting magnet main coil 3, and the fourth superconducting magnet main coil 4 of the superconducting magnet.

[0034] Preferably, Figure 3 As shown, the gradient device 13 includes three-axis actively shielded gradient coils, which are Figure 4a The X-gradient coil 13a shown, Figure 4b The Y gradient coil 13b shown, Figure 4c The Z gradient coil 13c shown, each coil includes two sub-coils, namely a main coil and a shielding coil, wherein the conducting wire of the Z gradient coil 13c is a hollow circular tube structure, and cooling water flows inside.

[0035] Preferably, with the vertical line of the center of the axis of the gradient device 13 as a reference, the cylindrical shells where the shielding coils of the X gradient coil 13a, the Y gradient coil 13b and the Z gradient coil 13c are located are symmetrical about the vertical line, the cylindrical shells where the main coils of the X gradient coil 13a, the Y gradient coil 13b and the Z gradient coil 13c are located are asymmetrical about the vertical line, and the centers of the gradient magnetic field homogeneity areas of the X gradient coil 13a, the Y gradient coil 13b and the Z gradient coil 13c coincide with the center of the axis of the gradient device.

[0036] Preferably, the gradient device 13 is asymmetric about a vertical line at the center of the gradient device axis, and is stepped at one end, with the aperture decreasing from large to small. The larger aperture can accommodate the patient 17's shoulders, and the patient's head is located at the smaller aperture.

[0037] Preferably, the gradient device 13 is located in the warm hole of the superconducting magnet, and the axis of the superconducting magnet vacuum container 11 coincides with the axis of the gradient device 13 , and the centers of the axes coincide.

[0038] Preferably, after the superconducting magnet, the gradient device 13, the radio frequency coil 14 and the cabinet are integrated, the whole system can be moved, and the examination bed 16 can be towed on the frame 15 of the superconducting magnet and moved together as needed, or can be detached and moved separately.

[0039] Although the above describes the illustrative specific embodiments of the present invention to facilitate those skilled in the art to understand the present invention, and it should be clear that the present invention is not limited to the scope of the specific embodiments, for those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

Claims

1. A portable superconducting magnetic resonance imaging system, characterized in that: The invention comprises a superconducting magnet, a gradient device, a radio frequency coil, a cabinet, a frame and an examination bed. The superconducting magnet is arranged in a superconducting magnet vacuum cavity, the gradient device is arranged in a warm hole of the superconducting magnet vacuum cavity, the radio frequency coil is arranged in the hole of the gradient coil, the cabinet is arranged at the lower end of the superconducting magnet vacuum cavity and is placed on the frame; the superconducting magnet adopts a Stirling refrigerator for conduction cooling, the gradient device is an asymmetric structure, and the radio frequency coil supports the use of multi-channel parallel transmission; the examination bed is connected to one end of the warm hole of the superconducting magnet vacuum cavity; the superconducting magnet, the gradient device, the radio frequency coil and the cabinet are placed on a movable frame.

2. A portable superconducting magnetic resonance imaging system according to claim 1, characterized in that: The superconducting magnet comprises four main coils and four shielding coils. The shielding coils are located at the periphery of the main coils and are longer in axial direction than the main coils, thereby providing excellent magnetic field shielding performance.

3. A portable superconducting magnetic resonance imaging system according to claim 1, characterized in that: The main coil and shielding coil of the superconducting magnet are wound with magnesium diboride superconducting wire and connected in series with superconducting joints to form a closed loop.

4. A portable superconducting magnetic resonance imaging system according to claim 1, characterized in that: The main coil and shielding coil of the superconducting magnet are supported by only one frame, without the need for end plates, and are hoisted on the vacuum container at the end of the frame.

5. The portable superconducting magnetic resonance imaging system according to claim 1, characterized in that: The vacuum container of the superconducting magnet is stepped, with the apertures at both ends larger than the inner aperture.

6. A portable superconducting magnetic resonance imaging system according to claim 1, characterized in that: The Stirling refrigerator comprises two stages of cold heads, namely a primary cold head and a secondary cold head, wherein the primary cold head is fixed on the superconducting magnet cold shield, the secondary cold head is located inside the superconducting magnet cold shield, and a cold conducting belt is arranged on the secondary cold head and connected to the shielding coil and the main coil of the superconducting magnet.

7. A portable superconducting magnetic resonance imaging system according to claim 1, characterized in that: The gradient device comprises three-axis actively shielded gradient coils, namely, an X gradient coil, a Y gradient coil, and a Z gradient coil. Each coil comprises two sub-coils, namely, a main coil and a shielding coil. The conductor of the Z gradient coil is a hollow circular tube structure with cooling water flowing inside.

8. A portable superconducting magnetic resonance imaging system according to claim 7, characterized in that: Taking the vertical line of the center of the gradient device axis as a reference, the cylindrical shell where the shielding coil of the gradient coil is located is symmetrical about the vertical line, the cylindrical shell where the main coil of the gradient coil is located is asymmetrical about the vertical line, and the center of the gradient magnetic field homogeneity zone of the gradient coil coincides with the center of the gradient device axis.

9. The portable superconducting magnetic resonance imaging system according to claim 1, characterized in that: The gradient device is asymmetrical about a vertical line at the center of the gradient device axis, and is stepped at one end, with the aperture decreasing from large to small. The larger aperture can accommodate the patient's shoulder, and the patient's head is located at the smaller aperture.

10. The portable superconducting magnetic resonance imaging system according to claim 1, characterized in that: The gradient device is located in the warm hole of the superconducting magnet, the axis of the vacuum container of the superconducting magnet coincides with the axis of the gradient device, and the centers of the axes coincide.

11. The portable superconducting magnetic resonance imaging system according to claim 1, characterized in that: The examination bed can be towed on the frame of the superconducting magnet and moved together or detached and moved separately as needed.

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