Portable superconducting magnetic resonance imaging system

Abstract

This invention relates to a portable superconducting magnetic resonance imaging (MRI) system. The superconducting magnet employs a highly shielded electromagnetic design, compressing the 5-gauss line range to near the magnet's vacuum container. The superconducting magnet coil support structure utilizes an integrated design, effectively reducing the support structure's mass. The superconducting magnet coil is wound with magnesium diboride and uses superconducting connector technology to achieve closed-loop operation. The superconducting magnet cryogenic system uses a Stirling refrigerator for conductive cooling of the superconducting magnet coil, eliminating the need for additional compressor equipment. The gradient device employs an asymmetric stepped design, accommodating patient shoulder insertion. The horizontal superconducting magnet structure supports the use of multi-channel parallel-transmitting radio frequency (RF) coils. The superconducting magnet, gradient device, RF coils, and cabinet are housed on a mobile chassis that can tow an examination bed. This invention enables portable examination using a superconducting MRI system.

Description

Technical Field

[0001] This invention belongs to the field of superconducting electrical engineering, and specifically relates to a portable superconducting magnetic resonance imaging system for magnetic resonance imaging detection. Background Technology

[0002] Magnetic resonance imaging (MRI) technology is constantly evolving, with one important direction being its portability. Portable MRI addresses the shortcomings of conventional MRI machines in specialized applications, such as obstetrics, ICU, mobile devices, and monitoring. This trend towards miniaturization and portability is breaking down the barriers of radiology and imaging departments, transforming conventional MRI machines into intelligent bedside devices. Currently, portable MRI machines have gained market access and play an irreplaceable role in specialized applications. However, existing portable MRI machines primarily use permanent magnets to generate the main magnetic field, which suffers from low magnetic field strength, poor uniformity, and susceptibility to temperature-induced drift. In contrast, superconducting magnets can generate stronger and more uniform magnetic fields, and superconducting constant current operation ensures extremely high magnetic field stability. Decades ago, general-purpose medical permanent magnet MRI was upgraded to superconducting MRI, significantly improving key indicators such as magnetic field strength, uniformity, and stability, resulting in a marked improvement in image quality and gradually becoming the mainstream MRI technology. Referring to the development history of general-purpose magnetic resonance imaging technology, using superconducting magnets to replace permanent magnets, and realizing the portability of superconducting magnets through innovative design concepts, is expected to lead the technological trend of portable magnetic resonance imaging and significantly expand the scope of market applications.

[0003] Chinese invention patent application CN113143245A discloses a mobile magnetic resonance imaging (MRI) system, including a scanning mechanism, a connected cabinet, a mobile chassis, and a bed mechanism. The upper and lower plates of a permanent magnet generate the main magnetic field. Its overall technical method differs significantly from the superconducting MRI system of this invention. US invention patent application US20240361405A1 discloses a portable MRI device employing a C-shaped permanent magnet structure, which is moved via a cylindrical base. Currently, most portable MRI systems are based on permanent magnets. These magnets do not require cryogenic systems or electricity; their key lies in achieving lightweight design through lowering the magnetic field and optimizing the yoke. Summary of the Invention

[0004] Superconducting magnets offer significant improvements in magnetic field performance compared to permanent magnets. However, their application in portable magnetic resonance imaging (MRI) technology faces challenges. Key issues include eliminating the need for electrical equipment to maintain the superconducting magnet and achieving lightweight design. To address these technical challenges, this invention proposes a portable superconducting MRI system. This system integrates various components to form a portable MRI system, enabling the superconducting magnet to be mobile and further facilitating the portability of the entire system.

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

[0006] A portable superconducting magnetic resonance imaging system includes a superconducting magnet, a gradient device, a radio frequency coil, a cabinet, a frame, and an examination bed. The superconducting magnet is disposed in a vacuum chamber of the superconducting magnet, the gradient device is disposed in a temperature port of the vacuum chamber, the radio frequency coil is placed in a cavity of the gradient coil, and the cabinet is placed at the lower end of the vacuum chamber and mounted on the frame. The superconducting magnet is conductively cooled by a Stirling refrigerator, the gradient device has an asymmetric structure, and the radio frequency coil supports multi-channel parallel transmission. The examination bed is connected to one end of the temperature port of the vacuum chamber. The superconducting magnet, gradient device, radio frequency coil, and cabinet are placed on a movable frame.

[0007] Furthermore, the superconducting magnet includes four main coils and four shielding coils. The shielding coils are located on the outer periphery of the main coils and have a longer axial length than the main coils, providing excellent magnetic field shielding performance.

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

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

[0010] Furthermore, the vacuum container of the superconducting magnet is stepped, with the diameters at both ends being larger than the internal diameter.

[0011] Furthermore, the Stirling refrigerator includes two-stage cold heads, namely a primary cold head and a secondary cold head. 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. A cooling strip is arranged on the secondary cold head and connected to the shielding coil and the main coil of the superconducting magnet.

[0012] Furthermore, the gradient device includes three-axis actively shielded gradient coils, namely an X gradient coil, a Y gradient coil, and a Z gradient coil. Each coil includes 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.

[0013] Furthermore, taking the vertical line of the center of the gradient device axis as a reference, the cylindrical shell containing the shielding coil of the gradient coil is symmetrical about the vertical line, while the cylindrical shell containing the main coil of the gradient coil is asymmetrical about the vertical line. The center of the uniform gradient magnetic field region of the gradient coil coincides with the center of the gradient device axis.

[0014] Furthermore, the gradient device is asymmetrical about the vertical line of the center of the gradient device axis, and is stepped at one end, with the aperture decreasing in size. The larger aperture can accommodate the patient's shoulder, while the patient's head is located at the smaller aperture.

[0015] Furthermore, the gradient device is located in the temperature hole of the superconducting magnet, and the axis of the vacuum container of the superconducting magnet and the axis of the gradient device coincide, with the center of the axis coinciding.

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

[0017] Beneficial effects:

[0018] While current portable permanent magnet magnetic resonance imaging (MRI) systems are showing promise in areas such as rapid disease screening, the need to improve image quality remains a key research focus. This invention utilizes magnesium diboride to increase the operating temperature of the superconducting coil, leveraging its multi-wire structure and superconducting connector technology to achieve closed-loop stable operation. By employing a Stirling refrigerator and a compact design for the superconducting magnet, the superconducting magnet is made portable, further enabling the portability of the entire system. This portable superconducting MRI system significantly outperforms current portable permanent magnet MRI systems in key indicators such as magnetic field strength, uniformity, and stability, supporting the production of high signal-to-noise ratio, high-resolution images, thus greatly expanding the application scope of portable MRI technology. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the portable superconducting magnetic resonance imaging system of the present invention. To show the internal structure, the superconducting magnet and gradient device are modeled in half.

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

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

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

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

[0024] Figure 4c This is a schematic diagram of the Z-gradient coil.

[0025] Explanation of reference numerals in the attached figures: 1 is the main coil of the first superconducting magnet, 2 is the main coil of the second superconducting magnet, 3 is the main coil of the third superconducting magnet, 4 is the main coil of the fourth superconducting magnet, 5 is the shielding coil of the first superconducting magnet, 6 is the shielding coil of the second superconducting magnet, 7 is the shielding coil of the third superconducting magnet, 8 is the shielding coil of the fourth superconducting magnet, 9 is the superconducting magnet coil frame, 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 Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this 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 this embodiment, the superconducting magnet is conductively cooled by a Stirling refrigerator 12, eliminating the need for a compressor; the gradient device 13 has an asymmetric structure; it supports the use of multi-channel parallel transmission radio frequency coils 14; the required spectrometer, gradient power amplifier, radio frequency power amplifier, water chiller, and battery are integrated into a single 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, which can tow the examination bed 16. The gradient device 13 is placed in the temperature port of the superconducting magnet vacuum chamber 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 chamber 11 and mounted on the frame 15, and the examination bed 16 is connected to one end of the temperature port of the superconducting magnet vacuum chamber 11.

[0028] like Figure 2As shown, the superconducting magnet comprises four main coils and four shielding coils. The shielding coils are located on the outer periphery of the main coils and have an axial length greater than that of the main coils, providing excellent magnetic field shielding performance. The main coils are designated as first superconducting magnet main coil 1, second superconducting magnet main coil 2, third superconducting magnet main coil 3, and fourth superconducting magnet main coil 4. The superconducting magnet main coils are arranged from one end of the superconducting magnet to the other in the following order: first superconducting magnet main coil 1, second superconducting magnet main coil 2, third superconducting magnet main coil 3, and fourth superconducting magnet main coil 4. 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 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. 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 located on the outer 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, respectively, 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, thus providing excellent magnetic field shielding performance.

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

[0031] Preferably, the main coil and shielding coil of the superconducting magnet are supported by only one superconducting magnet coil frame 9, without the need for end plates, and are suspended from the end of the superconducting magnet coil frame 9 onto the superconducting magnet vacuum container 11.

[0032] Preferably, the superconducting magnet vacuum container 11 is stepped, with the diameters at both ends being larger than the internal diameter.

[0033] Preferably, the Stirling refrigerator 12 includes two-stage cold heads, namely a primary cold head and a secondary cold head. 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. A cooling strip is arranged on the secondary cold head and 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 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.

[0034] Preferred, such as Figure 3 As shown, the gradient device 13 includes triaxially actively shielded gradient coils, which are respectively Figure 4a The X gradient coil 13a shown is shown. Figure 4b The Y gradient coil 13b shown is shown. Figure 4c The Z-gradient coil 13c shown contains two sub-coils, namely the main coil and the shielding coil. The conductor of the Z-gradient coil 13c is a hollow circular tube structure with cooling water flowing inside.

[0035] Preferably, with the vertical line of the center of the axis of the gradient device 13 as a reference, the cylindrical shells containing the shielding coils of the X gradient coil 13a, Y gradient coil 13b and Z gradient coil 13c are symmetrical about the vertical line, the cylindrical shells containing the main coils of the X gradient coil 13a, Y gradient coil 13b and Z gradient coil 13c are asymmetrical about the vertical line, and the center of the uniform gradient magnetic field region of the X gradient coil 13a, Y gradient coil 13b and Z gradient coil 13c coincides with the center of the axis of the gradient device.

[0036] Preferably, the gradient device 13 is asymmetrical about the vertical line of the center of the gradient device axis, and is stepped at one end with the aperture decreasing in size. The larger aperture can accommodate the shoulder of the patient 17 to enter, while the patient's head is located at the smaller aperture.

[0037] Preferably, the gradient device 13 is located in the temperature hole of the superconducting magnet, and the axis of the superconducting magnet vacuum container 11 and the axis of the gradient device 13 coincide, with the center of the axis coinciding.

[0038] Preferably, after integrating the superconducting magnet, gradient device 13, radio frequency coil 14, and cabinet, the entire system is movable. The examination bed 16 can be towed onto the frame 15 of the superconducting magnet and moved together as needed, or it can be detached and moved separately.

[0039] Although the illustrative specific embodiments of the present invention have been described above to enable those skilled in the art to understand the invention, it should be understood that the invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes will be obvious as long as they are within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of the present invention are protected.

Claims

1. A portable superconducting magnetic resonance imaging system, characterized in that: The system includes a superconducting magnet, a gradient device, a radio frequency coil, a cabinet, a frame, and an inspection bed. The superconducting magnet is housed within a vacuum chamber of the superconducting magnet. The gradient device is located within a temperature port of the vacuum chamber, and the radio frequency coil is placed within the port of the gradient device. The cabinet is positioned at the lower end of the vacuum chamber and mounted on the frame. The superconducting magnet is conductively cooled using a Stirling refrigerator. The gradient device has an asymmetric structure, and the radio frequency coil supports multi-channel parallel transmission. The inspection bed is connected to one end of the temperature port of the vacuum chamber. The superconducting magnet, gradient device, radio frequency coil, and cabinet are mounted on a movable frame. The superconducting magnet includes four main coils and four shielding coils. The shielding coils are located on the outer periphery of the main coils and have a longer axial length than the main coils, providing excellent magnetic field shielding performance. The Stirling refrigerator includes two cold heads, namely a primary cold head and a secondary cold head. The primary cold head is fixed on the superconducting magnet cold screen, and the secondary cold head is located inside the superconducting magnet cold screen. A cooling strip is arranged on the secondary cold head and connected to the shielding coil and the main coil of the superconducting magnet. The examination bed can be towed onto the frame of the superconducting magnet and moved together, or it can be detached and moved separately, as needed.

2. The 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 a superconducting connector to form a closed loop.

3. The 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. The frame is suspended from the vacuum cavity of the superconducting magnet at the end.

4. A portable superconducting magnetic resonance imaging system according to claim 1, characterized in that: The vacuum cavity of the superconducting magnet is stepped, with the diameters at both ends being larger than the internal diameter.

5. A portable superconducting magnetic resonance imaging system according to claim 1, characterized in that: The gradient device includes three actively shielded gradient coils: an X gradient coil, a Y gradient coil, and a Z gradient coil. Each coil contains two sub-coils: a main coil and a shielding coil. The Z gradient coil has a hollow circular tube structure with cooling water flowing inside.

6. A portable superconducting magnetic resonance imaging system according to claim 5, characterized in that: With the vertical line at the center of the gradient device axis as a reference, the cylindrical shell containing the shielding coil of the gradient coil is symmetrical about the vertical line, while the cylindrical shell containing the main coil of the gradient coil is asymmetrical about the vertical line. The center of the uniform gradient magnetic field region of the gradient coil coincides with the center of the gradient device axis.

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

8. A portable superconducting magnetic resonance imaging system according to claim 1, characterized in that: The gradient device is located in the temperature hole of the superconducting magnet. The axis of the superconducting magnet vacuum cavity and the axis of the gradient device coincide, and the centers of the axes coincide.

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