CN117849681A - Magnet array structure of mobile nuclear magnetic resonance imaging - Google Patents
Magnet array structure of mobile nuclear magnetic resonance imaging Download PDFInfo
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- CN117849681A CN117849681A CN202410020733.5A CN202410020733A CN117849681A CN 117849681 A CN117849681 A CN 117849681A CN 202410020733 A CN202410020733 A CN 202410020733A CN 117849681 A CN117849681 A CN 117849681A
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- 238000013421 nuclear magnetic resonance imaging Methods 0.000 title claims abstract description 13
- 238000002595 magnetic resonance imaging Methods 0.000 claims abstract description 20
- 238000003491 array Methods 0.000 claims description 4
- 238000003384 imaging method Methods 0.000 description 11
- 238000000034 method Methods 0.000 description 5
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 4
- 238000001514 detection method Methods 0.000 description 3
- 230000035945 sensitivity Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 2
- 210000004872 soft tissue Anatomy 0.000 description 2
- 238000002604 ultrasonography Methods 0.000 description 2
- 238000005481 NMR spectroscopy Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 238000002059 diagnostic imaging Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 239000006247 magnetic powder Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 210000000056 organ Anatomy 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 210000001519 tissue Anatomy 0.000 description 1
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Abstract
The invention discloses a magnet array structure of mobile nuclear magnetic resonance imaging, which comprises a main magnet array and a compensation magnet array; the main magnet array comprises a first array and a second array which are symmetrically arranged, the first array and the second array comprise a plurality of main magnet groups, the axes of all the main magnet groups of the first array are intersected with the center of a first circle, the axes of all the main magnet groups of the second array are intersected with the center of a second circle, and the first circle and the second circle are coaxially arranged; the compensating magnet array is a cylindrical array, the compensating magnet array is positioned on the inner sides of the first array and the second array, and the axes of the compensating magnet array are collinear with the connecting line of the centers of the first circle and the second circle. The invention improves the field intensity and the uniformity of the magnetic field in the region by utilizing the conjugated magnetic ring structure, and the quality and the volume can meet the movable requirement, thereby having important significance for the miniaturization and the movement of the magnetic resonance imaging equipment.
Description
Technical Field
The invention relates to the field of magnetic resonance imaging, in particular to a magnet array structure of mobile nuclear magnetic resonance imaging.
Background
Modern medical imaging means mainly include endoscopes, X-ray imaging, ultrasound, magnetic resonance imaging, and the like. Magnetic resonance imaging generates images of organs in the body by using strong magnetic fields, magnetic field gradients and radio waves, and has a large monitoring range and high imaging quality compared with endoscopes; compared with X-ray imaging, it has no radiation and high soft tissue contrast; compared with ultrasound, the ultrasonic imaging device has high resolution, can acquire three-dimensional information, and is suitable for imaging non-osseous parts or soft tissues of a human body.
However, the conventional magnetic resonance imaging apparatus is bulky, and it is difficult to realize timely diagnosis in emergency situations, and in order to solve this problem, a mobile magnetic resonance imaging system has been proposed. Compared with standard magnetic resonance imaging, the mobile magnetic resonance imaging magnetic field is smaller, the whole structure of the equipment is more simplified, and the mobile magnetic resonance imaging magnetic field has the advantages of easiness in scanning, economy, low energy consumption, light weight and the like, and can meet the requirements of imaging rapidness and image definition. In order to meet the mobile requirement, the physical size of the whole equipment needs to be greatly reduced, and the permanent magnet array is the preferred mode for providing a magnetic field for mobile magnetic resonance imaging because of no power consumption and low cost.
On the premise of a certain magnetic field direction, the larmor precession frequency of hydrogen protons in the main magnetic field is equal to the frequency of the radio frequency field, and the application of the radio frequency field perpendicular to the main magnetic field direction can deflect the hydrogen protons, so that a useful nuclear magnetic resonance signal is generated in the recovery process after the deflection. If the magnetic field is not uniform within a certain range, the larmor precession frequency of hydrogen protons contained in the same mass within the range is not the same, and when gradient field layer selection is used, signal interference caused by nearby deflected hydrogen protons is likely to occur. One of the most important parts of a magnetic resonance system is therefore the magnet, which aims to provide a stable magnetic field environment. Theoretically, the larger the field intensity is, the more uniform the distribution is, the better the quality of the obtained image is, but as the field intensity is increased, the larger the magnet volume is, the heavier the weight is, the higher the manufacturing cost is, the uniformity is difficult to ensure, and the field intensity of the mobile magnetic resonance imaging system which can be realized at present is limited.
Disclosure of Invention
The invention aims to provide a movable magnetic resonance imaging magnet array structure to solve the problems in the prior art, and the invention utilizes a conjugated magnetic ring structure to improve field intensity and magnetic field uniformity in a region, and the quality and the volume can meet movable requirements, thereby having important significance for miniaturization and mobility of magnetic resonance imaging equipment.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a magnet array structure of mobile nuclear magnetic resonance imaging comprises a main magnet array and a compensation magnet array;
the main magnet array comprises a first array and a second array which are symmetrically arranged, the first array and the second array comprise a plurality of main magnet groups, the axes of all the main magnet groups of the first array are intersected with the center of a first circle, the axes of all the main magnet groups of the second array are intersected with the center of a second circle, and the first circle and the second circle are coaxially arranged;
the compensating magnet array is a cylindrical array, the compensating magnet array is positioned on the inner sides of the first array and the second array, and the axes of the compensating magnet array are collinear with the connecting line of the centers of the first circle and the second circle.
Further, the compensation magnet array comprises a plurality of strip-shaped compensation magnet groups, and the plurality of strip-shaped compensation magnet groups form a cylindrical array.
Further, the bucking magnet array includes 18 bar bucking magnet sets.
Further, the first and second arrays each include 16 main magnet sets.
Further, the magnetic resonance imaging device also comprises a gradient coil, wherein the gradient coil is positioned on the inner side of the compensation magnet array;
the gradient coil comprises a first coil and a second coil which are symmetrically arranged, the first coil and the second coil comprise four saddle-shaped coils and Maxwell coils arranged on the outer sides of the four saddle-shaped coils, and the directions of the Maxwell coils of the first coil and the second coil are opposite.
Further, the saddle-shaped coil comprises two straight lines and two arcs, and the two arcs are respectively connected with one end and the other end of the two straight lines.
Further, four saddle-shaped coils are symmetrically arranged to form a cylinder, gaps are arranged between adjacent saddle-shaped coils, and the Maxwell coils are located on the outer side of the cylinder.
Further, the maxwell coil is located at the middle position of the cylinder.
Further, the outer side of the Maxwell coil is close to the inner side of the cylindrical array, and a gap is arranged between the outer side of the Maxwell coil and the inner side of the cylindrical array.
Further, the current directions in the first coil and the second coil are opposite.
Compared with the prior art, the invention has the beneficial effects that:
the main magnet array and the compensation magnet array are concentric arrays, the compensation magnet array is positioned at the inner side of the main magnet array, the main magnet array and the compensation magnet array are utilized to control the size and uniformity of a space magnetic field, the size of the space magnetic field is stably controlled to be about 120mT, the scanning time is shortened, and the detection sensitivity and the spatial resolution are improved. The invention is a magnet array structure for realizing mobile magnetic resonance imaging based on a conjugate magnetic ring array, improves the size and the magnetic field uniformity of a space magnetic field, shortens the scanning time, improves the detection sensitivity and the space resolution, and enhances the imaging definition. The magnet array has the characteristics of small structure volume, relatively light weight, low cost, integration and portability.
Furthermore, the invention also comprises a gradient coil, the gradient coil is positioned at the inner side of the compensation magnet array, and the current in the gradient coil is changed, so that a gradient field capable of encoding is provided for three-dimensional space imaging, tissues placed in the magnetic field are divided into three-dimensional grid structures, and the larger magnetic field gradient is equivalent to the generation of a larger scale in the three-dimensional space in the direction, so that the positioning capability and the encoding capability are further improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention.
FIG. 1 (a) is a perspective view of a magnet array structure of a mobile nuclear magnetic resonance imaging system without gradient coils according to the present invention;
FIG. 1 (b) is a top view of a magnet array configuration of mobile nuclear magnetic resonance imaging without gradient coils according to the present invention;
FIG. 1 (c) is a side view of a magnet array configuration of mobile nuclear magnetic resonance imaging without gradient coils in accordance with the present invention;
FIG. 2 (a) is a top view of the main magnet array structure of the present invention;
FIG. 2 (b) is a side view of the main magnet array structure of the present invention;
FIG. 3 (a) is a top view of a bucking magnet array structure according to the present invention;
FIG. 3 (b) is a side view of the bucking magnet array structure of the present invention;
FIG. 4 (a) is a perspective view of a magnet array structure for mobile MRI with gradient coils according to the present invention;
FIG. 4 (b) is a top view of a magnetic array structure for mobile nuclear magnetic resonance imaging with gradient coils according to the present invention;
FIG. 4 (c) is a side view of a magnet array configuration of the gradient coil-containing mobile nuclear magnetic resonance imaging of the present invention;
FIG. 5 (a) is a top view of the gradient coil structure of the present invention;
fig. 5 (b) is a side view of the gradient coil structure of the present invention.
Wherein 1 is a main magnet array; 2 is a compensation magnet array; and 3 is a gradient coil.
Detailed Description
In order that those skilled in the art may better understand the present invention, a further detailed description of the present invention will be provided with reference to the accompanying drawings, which are intended to illustrate, but not to limit, the present invention.
It should be noted that the terms "comprises" and "comprising," along with any variations thereof, in the description and claims of the present invention are intended to cover a non-exclusive inclusion, such as a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed or inherent to such process, method, article, or apparatus.
Example 1
The invention provides a magnet array structure of mobile nuclear magnetic resonance imaging, which comprises a main magnet array 1 and a compensation magnet array 2. The main magnet array 1 is used for generating a high-intensity magnetic field required in space, and the compensation magnet array 2 is based on the magnetic field design of the main magnet array 1, and corrects and compensates the uneven magnetic field generated by the main magnet array 1, so that the magnetic field generated in the area approximates to an ideal uniform magnetic field. The magnetic fields generated by the main magnet array 1 and the compensation magnet array 2 are overlapped to generate a larger uniform and stable magnetic field on a radial tangential plane, so that the scanning time can be shortened, the detection sensitivity and the spatial resolution can be improved, and the imaging definition can be enhanced.
Specifically, the invention controls the space magnetic field by using the main magnet array 1 and the compensating magnet array 2, controls the space magnetic field to be about 120mT, improves the coding capacity, and further realizes clearer imaging, wherein the main magnet array 1 and the compensating magnet array 2 are concentric arrays, the compensating magnet array 2 is positioned at the inner side of the main magnet array 1, the main magnet array 1 is shown in fig. 2 (a) and fig. 2 (b), and the compensating magnet array 2 is shown in fig. 3 (a) and fig. 3 (b); in order to achieve the scheme, the method comprises the steps of placing the crushed magnetic powder into a grinding tool, orienting by an external magnetic field, and pressing the mixture to fix the magnetic direction. In view of manufacturing and transportation problems, the main magnet array 1 and the compensation magnet array 2 are respectively composed of a main magnet group and a compensation magnet group, wherein the main magnet group and the compensation magnet group are composed of a plurality of single magnets, and the side length of each single magnet is limited to be within 4 cm. Finally, a mechanical structure is designed, and the permanent magnet array is assembled according to the structure shown in fig. 1 (a), 1 (b) and 1 (c) to form a magnet system.
Example 2
A magnet array structure for mobile nuclear magnetic resonance imaging, as shown in fig. 4 (a), 4 (b) and 4 (c), includes a main magnet array 1, a compensation magnet array 2 and a gradient coil 3;
the main magnet array 1 comprises a first array and a second array which are symmetrically arranged, wherein each of the first array and the second array comprises 16 main magnets, the axes of all main magnets of the first array are intersected with the center of a first circle, the axes of all main magnets of the second array are intersected with the center of a second circle, and the first circle and the second circle are coaxially arranged, as shown in fig. 2 (a) and 2 (b);
the compensating magnet array 2 comprises 18 bar-shaped compensating magnet groups, a plurality of bar-shaped compensating magnet groups form a cylindrical array, the compensating magnet array 2 is positioned on the inner sides of the first array and the second array, and the axes of the compensating magnet array 2 are collinear with the connecting lines of the centers of the first circle and the second circle, as shown in fig. 3 (a) and 3 (b);
the gradient coil 3 is located the inboard of compensation magnet array 2, the gradient coil 3 includes the first coil and the second coil that the symmetry set up, first coil and second coil all include four saddle coils and set up one maxwell coil in four saddle coils outsides, and the maxwell coil opposite direction of first coil and second coil, saddle coil includes two straight lines and two pitch lines, and two pitch lines connect respectively in the one end and the other end of two straight lines, four saddle coils symmetry sets up and forms the cylinder, and is provided with the clearance between the adjacent saddle coils, maxwell coil is located the cylinder outside, maxwell coil is located the middle part position of cylinder, maxwell coil's outside is close to the inboard of cylindricality array and is provided with the gap between the two, the electric current direction is opposite in first coil and the second coil, as shown in fig. 5 (a) and 5 (b).
The main magnet array 1 of the invention increases the regional magnetic field to the required size, and generates a uniform and stable magnetic field on a radial tangential plane and generates a constant magnetic field gradient in an axial direction by utilizing the correction and compensation actions of the compensation magnet array 2 and the capability of the gradient coil 3 to generate a linear magnetic field. The structure has good coding capability, improves the definition of subsequent imaging, and provides convenience for miniaturization and mobility of magnetic resonance imaging equipment.
It will be appreciated by those skilled in the art that the present invention can be carried out in other embodiments without departing from the spirit or essential characteristics thereof. Accordingly, the above disclosed embodiments are illustrative in all respects, and not exclusive. All changes that come within the scope of the invention or equivalents thereto are intended to be embraced therein.
Claims (10)
1. A magnet array structure for mobile nuclear magnetic resonance imaging, characterized by comprising a main magnet array (1) and a compensation magnet array (2);
the main magnet array (1) comprises a first array and a second array which are symmetrically arranged, the first array and the second array comprise a plurality of main magnet groups, the axes of all the main magnet groups of the first array are intersected with the center of a first circle, the axes of all the main magnet groups of the second array are intersected with the center of a second circle, and the first circle and the second circle are coaxially arranged;
the compensating magnet array (2) is a cylindrical array, the compensating magnet array (2) is positioned on the inner sides of the first array and the second array, and the axis of the compensating magnet array (2) is collinear with the connecting line of the centers of the first circle and the second circle.
2. A mobile magnetic resonance imaging magnet array structure according to claim 1, characterized in that the compensation magnet array (2) comprises a number of bar-shaped compensation magnet groups, which form a cylindrical array.
3. A mobile magnetic resonance imaging magnet array structure according to claim 2, characterized in that the bucking magnet array (2) comprises 18 bar bucking magnet sets.
4. A mobile mri magnet array configuration according to claim 1, wherein said first and second arrays each comprise 16 main magnet sets.
5. A mobile magnetic resonance imaging magnet array structure according to claim 1, characterized by further comprising gradient coils (3), the gradient coils (3) being located inside the compensation magnet array (2);
the gradient coil (3) comprises a first coil and a second coil which are symmetrically arranged, the first coil and the second coil comprise four saddle-shaped coils and Maxwell coils which are arranged outside the four saddle-shaped coils, and the directions of the Maxwell coils of the first coil and the second coil are opposite.
6. A mobile mri magnet array configuration according to claim 5 wherein said saddle coil comprises two straight lines and two arcs, said two arcs being connected at one end and at the other end of said two straight lines, respectively.
7. A mobile mri magnet array structure according to claim 6, wherein four of said saddle-shaped coils are symmetrically arranged to form a cylinder, and gaps are provided between adjacent saddle-shaped coils, said maxwell coils being located outside the cylinder.
8. A mobile mri magnet array configuration according to claim 7, wherein said maxwell coil is located in a central position of the cylinder.
9. A mobile mri magnet array structure according to claim 7, wherein said maxwell coil has an outer side which is adjacent to an inner side of the cylindrical array with a gap therebetween.
10. A mobile mri magnet array configuration according to claim 5, wherein the current flow in said first and second coils is in opposite directions.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202410020733.5A CN117849681A (en) | 2024-01-05 | 2024-01-05 | Magnet array structure of mobile nuclear magnetic resonance imaging |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202410020733.5A CN117849681A (en) | 2024-01-05 | 2024-01-05 | Magnet array structure of mobile nuclear magnetic resonance imaging |
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| CN117849681A true CN117849681A (en) | 2024-04-09 |
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| CN202410020733.5A Pending CN117849681A (en) | 2024-01-05 | 2024-01-05 | Magnet array structure of mobile nuclear magnetic resonance imaging |
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