Unilateral magnet rotating magnetic particle imaging device and method

Abstract

The present invention belongs to the field of biomedical imaging technology, and specifically relates to a unilateral magnet rotating magnetic particle imaging device and method. The device aims to address the problem that electrically driving an FFP with a coil can only change its position within a small range, limiting its imaging field of view. The present invention comprises: a permanent magnet array for generating a magnetic field-free point; a horizontal drive coil disposed within the array's internal array of the permanent magnet array; a depth drive coil disposed within the array's horizontal drive coil; a receiving coil for receiving magnetic particles to generate a nonlinear response signal; and an angle adjustment device for mounting the permanent magnet array. The horizontal drive coil, depth drive coil, receiving coil, and angle adjustment device are all mounted on a horizontal movement device for changing the position of the magnetic field-free point on the horizontal plane. The present invention can change the position of the FFP by adjusting the permanent magnet's tilt angle and position, thereby expanding the imaging range while reducing coil requirements and system power consumption, thereby achieving better imaging results.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomedical imaging, and in particular relates to a unilateral magnet rotating magnetic particle imaging device and method. Background Art

[0002] Magnetic particle imaging (MPI), a cutting-edge non-invasive in vivo tomography technology, emerged in 2005. This technology cleverly uses the static gradient field of the magnetic field to construct a unique magnetic field free point (FFP) or magnetic field free line (FFL), and through the action of the driving field, the magnetic field-free area can be flexibly moved. Subsequently, the excitation coil excites the magnetic particles to produce a nonlinear response signal, thereby achieving precise imaging of the concentration distribution of magnetic nanoparticles. It is worth mentioning that MPI technology does not rely on radioactive tracers. Therefore, it has shown great application potential in many medical fields such as angiography, cell tracing, cancer diagnosis and treatment, and has attracted much attention from the medical community.

[0003] There are various ways to construct the selection field in magnetic particle imaging devices, which are mainly divided into bilateral symmetrical structures and unilateral asymmetrical structures. The unilateral asymmetrical structure is simple and compact, and its position can be changed by mechanical devices or manpower to obtain a larger imaging range. However, in order to constrain its volume, only a limited number of permanent magnets or coils can be placed. At the same time, the magnetic field distribution decays with increasing distance, resulting in depth limitations for imaging deeper into the human body. In contrast, the bilateral symmetrical structure is not limited by the number of magnets, and the selection field has high linearity. However, when achieving large field of view imaging, its structural design becomes complicated, resulting in a large device size and high power consumption. In addition, as the field of view increases, the selection field gradient decreases, and the imaging quality is also affected.

[0004] The development of magnetic particle imaging technology has shown tremendous potential in the medical field. In thermal ablation treatment for liver cancer, MPI has the potential to monitor temperature changes in the liver's lesions in real time, providing precise feedback for treatment. In the diagnosis of coronary plaque inflammation, MPI can also enable non-invasive, real-time diagnosis of inflammation severity. However, achieving human-scale imaging remains a key challenge in the development of magnetic particle imaging technology.

[0005] In cancer diagnosis and treatment monitoring, magnetic particle imaging technology allows doctors to observe the location, size, and shape of tumors in real time and noninvasively, as well as changes during treatment. This helps doctors better assess treatment effectiveness and develop more effective treatment plans. Furthermore, in angiography, magnetic particle imaging technology eliminates the need for radioactive tracers, reducing the risk of radioactive exposure to patients. This technology is crucial for the diagnosis and treatment of conditions such as cardiovascular and cerebrovascular diseases. Furthermore, in cell tracking and cell therapy monitoring, magnetic particle imaging technology can track the distribution and migration of transplanted cells within the body, as well as the effectiveness of cell therapy. This is crucial for studying the mechanisms of cell therapy, optimizing treatment plans, and evaluating treatment outcomes. Furthermore, in precision magnetic hyperthermia, magnetic particle imaging technology can monitor the temperature changes and distribution of magnetic nanoparticles in real time during treatment, ensuring precise targeting of the lesion and minimizing damage to surrounding normal tissue.

[0006] Looking ahead, with the continuous advancement of technology, we have reason to believe that magnetic particle imaging will play an even more important role in medicine, providing more accurate and efficient solutions for the diagnosis and treatment of diseases. At the same time, we also look forward to seeing more innovative structural designs that overcome the limitations of existing technology and push magnetic particle imaging technology to new heights.

[0007] However, despite the enormous potential of magnetic particle imaging technology in various fields, achieving real-time imaging within the human field of view remains a pressing challenge in its development. Furthermore, in unilateral MPI imaging, the large magnetic field gradient generated by the permanent magnets means that the FFP can only be repositioned within a small range via the coils, limiting the imaging field of view. Currently, due to limitations in device structure, magnetic field distribution, and data processing, magnetic particle imaging technology still has certain limitations in practical applications.

[0008] Based on this, the present invention proposes a unilateral magnet rotating magnetic particle imaging device and method. Summary of the Invention

[0009] In order to solve the above-mentioned problem in the prior art, that is, the position of the FFP can only be changed in a small range by electrically driving the coil, which limits its imaging field of view, the present invention provides a unilateral magnet rotating magnetic particle imaging device and method.

[0010] A first aspect of the present invention provides a unilateral magnet rotating magnetic particle imaging device comprising a permanent magnet array, a horizontal drive coil, a depth drive coil, a receiving coil, an angle adjustment device, and a horizontal movement device;

[0011] The permanent magnet array is used to generate a magnetic field-free point. A horizontal drive coil is arranged in an array inside the permanent magnet array. The horizontal drive coil is used to move the magnetic field-free point and excite magnetic particles to generate a nonlinear response signal. A depth drive coil is arranged inside the horizontal drive coil arranged in the array. The depth drive coil is used to generate a uniform magnetic field that changes uniformly and drive the magnetic field-free point to move along the Z-axis direction. The Z-axis direction is the axial direction of the depth drive coil.

[0012] The receiving coil is used to receive magnetic particles to generate a nonlinear response signal; the permanent magnet array is installed in the angle adjustment device, and the angle adjustment device is used to adjust the angle of each permanent magnet in the permanent magnet array;

[0013] The horizontal drive coil, the depth drive coil, the receiving coil and the angle adjustment device are all installed on a horizontal moving device. The horizontal moving device changes the position of the magnetic field-free point on the horizontal plane by changing the positions of the permanent magnet array, the horizontal drive coil and the depth drive coil.

[0014] In some preferred embodiments, the angle adjustment device includes a permanent magnet housing, a disk, a connecting rod, a universal joint, and a housing;

[0015] Each permanent magnet in the permanent magnet array is respectively installed in a permanent magnet shell, one side of the permanent magnet shell is fixed to one end of a connecting rod, the other end of the connecting rod is overlapped on the disk, and the disk is connected to a driving device, and the driving device is used to drive the disk to move along the Z-axis direction;

[0016] A universal joint is installed on the other side of the permanent magnet shell. The universal joint is arranged in a ball groove and rotates along the ball groove. The ball groove is opened on the inner surface of the shell.

[0017] In some preferred embodiments, the driving device includes an end cap, a screw hole, a screw and a ball seat;

[0018] The end cover is arranged above the housing, and a screw hole is opened in the center of the end cover, the screw hole is threadedly connected to the screw, and the screw is coaxially fixed to the disc;

[0019] A ball seat is installed on the surface of the end cover on the side close to the universal joint. The ball seat is installed on the universal joint and is used to limit the range of movement of the universal joint.

[0020] In some preferred embodiments, the horizontal movement device includes a gear and a ring gear;

[0021] A horizontal driving coil, a depth driving coil, the receiving coil and an angle adjustment device are installed on the surface of the gear. The gear is engaged with a gear ring, and the gear ring is installed on the slide rail of the operating table.

[0022] In some preferred embodiments, the axis of the horizontal drive coil and the axis of the depth drive coil are arranged in parallel.

[0023] In some preferred embodiments, a universal joint is installed on the other side of the permanent magnet housing, and its specific structure is as follows:

[0024] The other side of the permanent magnet shell is fixed to one end of the connecting block, and the other end of the connecting block is fixed to the universal joint.

[0025] In some preferred embodiments, the permanent magnets in the permanent magnet array, the permanent magnet housing, the connecting rod, the connecting block, the universal joint and the ball seat are all distributed in a circular array along the axis of the depth drive coil.

[0026] In some preferred embodiments, the number and angle of the annular array distribution of the permanent magnet housing, the connecting rod, the connecting block, the universal joint and the ball seat correspond one-to-one to the number and angle of the annular array distribution of the permanent magnet array.

[0027] Another aspect of the present invention provides a unilateral magnet rotating magnetic particle imaging method based on a unilateral magnet rotating magnetic particle imaging device, the method comprising:

[0028] Step S1: placing the object to be measured containing magnetic nanoparticles on the central axis of the device, installing the permanent magnet array into the angle adjustment device based on the position of the object to be measured, and adjusting the tilt angle of the permanent magnet array so that the generated magnetic field-free point is close to the target area in depth;

[0029] Step S2, installing the angle adjustment device, the horizontal drive coil, the depth drive coil, and the receiving coil in the horizontal moving device, and adjusting the size of the imaging field of view by the horizontal moving device;

[0030] Step S3: Current is passed through the depth drive coil to cause the zero-magnetic field point generated by the permanent magnet array to move back and forth in the Z-axis direction. Simultaneously, current is passed through the horizontal drive coil to cause the zero-magnetic field point to move in a horizontal plane perpendicular to the Z-axis, with a motion component perpendicular to the Z-axis, and to stimulate an MPI signal.

[0031] Step S4, receiving the MPI signal based on the receiving coil and sending it to the computer for image reconstruction to form a three-dimensional MPI image;

[0032] Step S5: Determine whether a slide rail is needed to perform imaging over a wider range based on the size of the object being measured and the imaging location. If so, adjust the slide rail position and jump to step S3 to restart imaging. If not, determine whether the depth of the magnetic field-free point needs to be changed.

[0033] If necessary, the angle adjustment device is used to adjust the tilt angle of the permanent magnet array so that the magnetic field-free point reaches another depth, and the process jumps to step S3 to restart imaging until the depth does not need to be changed, and then the imaging is ended; if not, the imaging is ended directly.

[0034] In some preferred embodiments, a three-dimensional MPI image is formed by image reconstruction, and specific methods thereof include a system matrix method or an X-space method.

[0035] Beneficial effects of the present invention:

[0036] The designed mechanical structure can change the position of the magnetic field-free area generated by the permanent magnet over a large range, thereby achieving an imaging range on the scale of the human body. The simultaneously configured horizontal drive coil and depth drive coil can perform rapid electrical scanning within a small range while being mechanically driven, thereby improving the overall imaging speed. The overall design is a unilateral device, with all parts on one side of the object to be imaged. It consists of a permanent magnet array that generates a magnetic field-free point (FFP), a depth coil that drives the FFP to move within a small range in the depth direction, and several pairs of orthogonal excitation coils that drive the FFP to move within a small range in the two-dimensional plane, as well as a supporting mechanical structure that can enable the FFP to move over a large range.

[0037] This design combines the advantages of a bilaterally symmetrical structure with a large magnetic field gradient and a unilateral structure with flexibility and a large imaging range. Several pairs of orthogonal excitation coils and a depth coil are designed to achieve fast three-dimensional scanning of the FFP in a small range. In addition, the FFP position can be changed by adjusting the tilt angle and horizontal position of the permanent magnet through the mechanical structure, thereby expanding the imaging range while reducing the requirements for the drive coil and lowering the system power consumption, thereby achieving better imaging effects.

[0038] This design has a simple structure and is easy to operate. During the imaging scan, adjusting the mechanical structure in the imaging system can image the entire object being measured over a larger range, and adjusting the excitation frequency of the mechanical structure or coil current can achieve a scanning trajectory with variable density. This device and method can improve the imaging resolution of unilateral MPI, reduce system power consumption, and increase imaging speed, thereby achieving the purpose of human-scale MPI imaging.

[0039] All structures of the present invention together constitute a unilateral magnet rotation imaging device, in which the FFP position is driven by a combination of mechanical and electrical drive. Specifically, large-scale FFP position changes can be achieved by mechanically changing the tilt angle of the permanent magnets to alter the FFP depth, while the horizontal position of the permanent magnet array can be altered by meshing the gear rings to change the FFP position in the XY plane. Small-scale FFP position changes can be achieved by passing specific currents through the depth drive coil and the horizontal drive coil. This design combines the advantages of mechanical motion imaging, including a wide field of view, low power consumption, and minimal impact on the magnetic field gradient, with the high speed of electrical scanning. It also significantly mitigates the shortcomings of both, thereby achieving better imaging results. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Other features, objects and advantages of the present application will become more apparent upon reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0041] Figure 1 This is a schematic diagram of the position distribution of each coil of a unilateral magnet rotating magnetic particle imaging device of the present invention;

[0042] Figure 2 This is a schematic diagram of the overall external structure of an angle adjustment device in a unilateral magnet rotating magnetic particle imaging device of the present invention;

[0043] Figure 3 This is a cross-sectional view of the internal structure of an angle adjustment device in a unilateral magnet rotating magnetic particle imaging device of the present invention;

[0044] Figure 4 This is an axonometric diagram of the internal structure of an angle adjustment device in a unilateral magnet rotating magnetic particle imaging device of the present invention;

[0045] Figure 5 This is a schematic structural diagram of an end cover in a unilateral magnet rotating magnetic particle imaging device of the present invention;

[0046] Figure 6 It is a schematic diagram of a horizontal moving device in a unilateral magnet rotating magnetic particle imaging device of the present invention;

[0047] Figure 7 This is a schematic diagram of a horizontal moving device in a unilateral magnet rotating magnetic particle imaging device of the present invention installed on an operating table;

[0048] Figure 8 It is a schematic diagram of the motion trajectory of the non-magnetic field point when the geometric dimensions of the gear and the gear ring are changed in a unilateral magnet rotating magnetic particle imaging device of the present invention;

[0049] Figure 9 It is a schematic flow chart of a unilateral magnet rotating magnetic particle imaging method of the present invention;

[0050] Figure 10 It is a schematic diagram of the three-dimensional motion trajectory of the FFP in a small range after a predetermined current is passed through the depth coil and the horizontal drive coil in a unilateral magnet rotating magnetic particle imaging method of the present invention. DETAILED DESCRIPTION

[0051] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only portions relevant to the relevant invention are shown in the accompanying drawings.

[0052] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0053] like Figures 1-8 For details, see Figure 1 、 Figure 2 and Figure 6 The first embodiment of the present invention provides a unilateral magnet rotating magnetic particle imaging device, comprising a permanent magnet array 1, a horizontal drive coil 2, a depth drive coil 3, a receiving coil, an angle adjustment device 4 and a horizontal movement device 5;

[0054] The permanent magnet array 1 is used to generate a magnetic field-free point. A horizontal drive coil 2 is arranged in an array inside the permanent magnet array 1. The horizontal drive coil 2 is used to move the magnetic field-free point and excite the magnetic particles to generate a nonlinear response signal. A depth drive coil 3 is arranged inside the horizontal drive coil 2 arranged in an array. The depth drive coil 3 is used to generate a uniform magnetic field with uniform changes and drive the magnetic field-free point to move in a small range along the Z-axis direction. The Z-axis direction is the axial direction of the depth drive coil 3.

[0055] The receiving coil is used to receive magnetic particles to generate a nonlinear response signal; the permanent magnet array 1 is installed in the angle adjustment device 4, and the angle adjustment device 4 is used to adjust the angle of each permanent magnet in the permanent magnet array 1;

[0056] The horizontal drive coil 2, the depth drive coil 3, the receiving coil and the angle adjustment device 4 are all installed on the horizontal moving device 5. The horizontal moving device 5 changes the position of the magnetic field-free point on the horizontal plane by changing the position of the permanent magnet array 1, the horizontal drive coil 2 and the depth drive coil 3.

[0057] Among them, the permanent magnet array 1 in the present invention is composed of a number of bar-shaped permanent magnets, the number of which is preferably 12 in this embodiment, which is used to generate a magnetic field-free point. The matching angle adjustment device 4 can make all permanent magnets rotate at the same angle as required, thereby changing the position of the magnetic field-free point on the Z axis over a large range.

[0058] The depth driving coil 3 operates by passing a uniformly changing current, and is responsible for generating a uniform magnetic field that changes uniformly, driving the point without magnetic field to move in a small range along the Z axis.

[0059] In this embodiment, the horizontal driving coils 2 are preferably four pairs, eight in total, which move the FFP on a two-dimensional plane at the same depth and excite the magnetic particles to generate nonlinear response signals.

[0060] Among them, the function of the receiving coil is only to receive the magnetic particle response signal. The present invention does not limit its specific position. Any position that can receive the magnetic particle response signal can be installed and is also within the protection scope of the present invention.

[0061] This embodiment provides a specific location for the receiving coil, which is located below the permanent magnet array 1 and on the outermost side. In other words, from the bottom center of the permanent magnet array 1 outward, the order is the driving coil, the permanent magnet, and the receiving coil.

[0062] In this embodiment, the permanent magnet array 1 is defined as Y. The permanent magnet generates a field-free point (FFP) at a certain position on the central axis. The depth of the field-free point, that is, its position in the Z-axis direction, can be significantly adjusted by changing the tilt angle of the permanent magnet using the angle adjustment device 4. The position of the field-free point on the horizontal plane can be significantly adjusted using the horizontal adjustment device 5.

[0063] The depth drive coil 3 is responsible for generating a uniform field and driving the no-magnetic field point to move in the Z-axis direction. It is named Cz. The magnetic field it generates can achieve the depth movement of the FFP in a small range after adjusting the tilt angle of the permanent magnet.

[0064] The four pairs of horizontal drive coils 2 are named C1, C2, C3, and C4. These four pairs of horizontal drive coils are responsible for moving the magnetic field-free point in the XY plane at a certain depth. The XY plane is a horizontal plane perpendicular to the Z axis. After the permanent magnet tilt angle is determined, the magnetic field generated by these coils can cooperate with the change of the current in the depth drive coil 3 to achieve a small range of three-dimensional movement of the magnetic field-free point. In addition, the magnetic field generated by the C1, C2, C3, and C4 coils is responsible for driving the two-dimensional movement of the magnetic field-free point and is also responsible for orthogonal excitation to generate the MPI excitation signal.

[0065] The receiving coil is named Cr and is responsible for sensing the MPI signal of the magnetic nanoparticles. For the sake of simplifying the drawing, the receiving coil is not marked in the schematic diagram, but the structure and position of the receiving coil are existing technologies and will not be described here.

[0066] The present invention uses an angle adjustment device 4 as a mechanical device for achieving angle adjustment, which can change the inclination angle of the permanent magnet so that the magnetic field-free point can move continuously on the Z axis. The following embodiment provides a specific structure of the angle adjustment device 4 that can be implemented:

[0067] For further explanation of the present invention, see Figure 2 、 Figure 3 and Figure 4 , the angle adjustment device 4 includes a permanent magnet shell 41, a disk 42, a connecting rod 43, a universal joint 44 and a housing 45;

[0068] Each permanent magnet in the permanent magnet array 1 is mounted in a permanent magnet housing 41. One side of the permanent magnet housing 41 is fixed to one end of a connecting rod 43. The other end of the connecting rod 43 is overlapped on the disk 42. The disk 42 is connected to a driving device, and the driving device is used to drive the disk 42 to move along the Z-axis direction.

[0069] A universal joint 44 is installed on the other side of the permanent magnet housing 41 . The universal joint 44 is disposed in a ball groove and rotates along the ball groove. The ball groove is provided on the inner surface of the outer shell 45 .

[0070] The angle adjustment device 4 for changing the inclination angle of the permanent magnet fixes each bar-shaped permanent magnet on a circle through the universal joint 44, while ensuring that all permanent magnets have the same inclination angle with the horizontal plane in each case. On this basis, the height of the disk 42 is adjusted to drive the connecting rod 42 to move up and down. Based on the angle adjustment of the universal joint 44, all permanent magnets can change the same inclination angle at the same time.

[0071] For further explanation of the present invention, see Figure 3 and Figure 5 , the driving device includes an end cover 46, a screw hole 47, a screw 48 and a ball seat 49;

[0072] The end cover 46 is disposed above the housing 45 . A screw hole 47 is formed in the center of the end cover 46 . The screw hole 47 is threadedly connected to the screw 48 . The screw 48 is coaxially fixed to the disc 42 .

[0073] A ball seat 49 is mounted on the surface of the end cover 46 on the side close to the universal joint 44 . The ball seat 49 is mounted on the universal joint 44 and is used to limit the range of motion of the universal joint 44 .

[0074] Among them, when the present invention is in use, the screw 48 can be manually rotated. Since the end cover 46 where the screw hole 47 is located is fixed, the screw 48 will move up and down, thereby driving the disc 42 to move up and down, thereby realizing the driving function. An electric rotating motor can also be coaxially installed on the screw 48, and all structures that can realize the up and down movement of the screw 48 can be used, thereby making the disc 42 located on the axis move up and down in the Z-axis direction, and then can push the connecting rod 43 connected to the permanent magnet array 1. The universal joint 14 is fixed at a fixed point, but can rotate around it, so that the permanent magnet housing 41 used to place the bar-shaped permanent magnet can be rotated at the same angle at the same time, and the generated FFP moves in depth but does not move in the other two directions.

[0075] Among them, after the present invention installs each permanent magnet in the permanent magnet array 1 in a permanent magnet shell 41 respectively, the horizontal drive coil 2 and the depth drive coil 3 are placed below the connecting rod 43 on the gear 51 according to the positional relationship between the above-mentioned horizontal drive coil 2, the depth drive coil 3 and the permanent magnet array 1, and are arranged between the permanent magnet shell 41 and the disk 42.

[0076] For further explanation of the present invention, see Figure 6 and Figure 7 , the horizontal moving device 5 includes a gear 51 and a ring gear 52;

[0077] The horizontal drive coil 2 , the depth drive coil 3 , the receiving coil and the angle adjustment device 4 are installed on the surface of the gear 51 . The gear 51 is engaged with a ring gear 52 , and the ring gear 52 is installed on the slide rail of the operating table 6 .

[0078] Among them, the slide rail of the operating table 6 is the existing technology, which can be a guide rail and slider mechanism, and its structure is not described here in detail.

[0079] A rotating shaft is coaxially fixed at the center of the gear 51 . The rotating shaft can be driven manually by an operator or by a servo motor, so that the gear 51 can roll in the gear ring 52 .

[0080] See also Figure 6-Figure 8The horizontal moving device 5 for changing the position of the magnetic field-free point on the XY plane is mainly composed of a ring gear 52 and a gear 51. The ring gear 52 is an inner ring gear. The remaining structure is set at a fixed position of the gear 51. Then, through the engagement of the ring gear 52 and the gear 51, the gear 51 is allowed to roll on the inside of the ring gear 52 without sliding, so that the remaining structure can change its position on the XY plane according to a certain path. Based on the current mechanical structure, assuming that the rolling speed of the gear 51 is 1m / s and the imaging field of view is a 40cm circle, in the sparse case where different scanning paths are required, the time for scanning a plane of a fixed depth is approximately 1-3 minutes. Adjusting the size of the ring gear 52 and the gear 51 or the position of the permanent magnet array 1 on the gear 51 can change the imaging field of view and the imaging trajectory.

[0081] The schematic diagram of the motion trajectory of the non-magnetic field point when the geometric dimensions of the gear 51 and the gear ring 52 are different and the permanent magnet array 1 is fixed at different positions of the gear is as follows: Figure 8 shown.

[0082] Among them, the remaining structure 8 is specifically referred to Figure 6 The remaining structure 8 includes a permanent magnet array 1, a horizontal drive coil 2, a depth drive coil 3, a receiving coil, and an angle adjustment device 4.

[0083] For further explanation of the present invention, see Figure 1 The axis of the horizontal driving coil 2 and the axis of the depth driving coil 3 are arranged in parallel.

[0084] For further explanation of the present invention, see Figure 3 , a universal joint 44 is installed on the other side of the permanent magnet shell 41, and its specific structure is as follows:

[0085] The other side of the permanent magnet housing 41 is fixed to one end of the connecting block 7 , and the other end of the connecting block 7 is fixed to the universal joint 44 .

[0086] For further explanation of the present invention, see Figure 1 and Figure 4 The permanent magnets in the permanent magnet array 1 , the permanent magnet shell 41 , the connecting rod 43 , the connecting block 7 , the universal joint 44 and the ball seat 49 are all distributed in a circular array along the axis of the depth drive coil 3 .

[0087] For further explanation of the present invention, see Figure 4 The number and angle of the circular array distribution of the permanent magnet shell 41, the connecting rod 43, the connecting block 7, the universal joint 44 and the ball seat 49 correspond one to one with the number and angle of the circular array distribution of the permanent magnet array 1.

[0088] like Figures 1-10For details, see Figure 9 The second embodiment of the present invention provides a unilateral magnet rotating magnetic particle imaging method based on a unilateral magnet rotating magnetic particle imaging device, the method comprising:

[0089] Step S1: Place the object to be measured containing magnetic nanoparticles on the central axis of the device. Based on the position of the object to be measured, install the permanent magnet array 1 into the angle adjustment device 4, and adjust the tilt angle of the permanent magnet array 1 so that the generated magnetic field-free point is close to the target area in depth.

[0090] The tilt angle of the permanent magnet array 1 is adjusted so that the generated FFP is at the same depth as the target area.

[0091] The center of the device is the central axis of the gear ring 52 .

[0092] The imaging field of view is adjusted by rolling the gear 51 inside the gear ring 52, thereby changing the horizontal position of the FFP at the same depth. The same depth can also be understood as the inclination angle of the permanent magnet array 1 remaining unchanged.

[0093] It should be noted that the imaging field of view is determined at the outset and depends on the geometric dimensions of the gear ring 52. Changing the relative dimensions of the gear 51 and the gear ring 52 and the position of the center of the permanent magnet array 1 on the gear 51 will change the scanning trajectory of the FFP in the horizontal plane.

[0094] Step S2: Install the angle adjustment device 4, the horizontal drive coil 2, the depth drive coil 3, and the receiving coil in the horizontal movement device 5. The horizontal movement device 5 is used to adjust the size of the imaging field of view so that the generated FFP can move over a large range within the XY plane at the depth determined in step S1.

[0095] The size of the gear ring 51 is approximately equal to the size of the imaging field of view in the horizontal direction.

[0096] Step S3: Current is passed through the depth drive coil 3 to make the magnetic field-free point generated by the permanent magnet array 1 move back and forth in a small range in the Z-axis direction. At the same time, current is passed through the horizontal drive coil 2 to make the magnetic field-free point move in a horizontal plane perpendicular to the Z-axis, with a motion component perpendicular to the Z-axis, and stimulate the MPI signal.

[0097] The purpose of step S3 is to change the position of the FFP and obtain magnetic nanoparticle signals at different positions to achieve the purpose of three-dimensional imaging.

[0098] Because the permanent magnet array 1 generates a large magnetic field gradient, electrically driven coils are incapable of significantly changing the FFP position. Therefore, a mechanical device is employed. To achieve large-scale FFP position changes, the tilt angle of the permanent magnet array 1 is varied in depth, while the gear 51 rolls within the ring gear 52 in the horizontal plane. To achieve small-scale FFP position changes, the depth coil is used in depth, while the horizontal drive coil 2 is used in the horizontal plane.

[0099] Combining the two, the scanning range can be changed over a large range using a mechanical structure, while all signals in a small area can be quickly acquired using electrical scanning each time.

[0100] The FFP can be moved three-dimensionally within a small range thanks to the combined action of the depth drive coil 3 and the four pairs of horizontal drive coils 2 (C1, C2, C3, and C4). The synchronized electrical scanning and mechanical movement allow the device to achieve both a larger imaging range through large-scale mechanical movement of the FFP and a denser scanning trajectory through electrical scanning.

[0101] Specifically, see Figure 1AC is passed through the Cz coil, causing the FFP generated by the permanent magnet array to reciprocate within a small depth range. The current flowing through the Cz coil is fz × (tT / 2), where fz is a constant, meaning the FFP moves at a constant speed in the depth direction; T is the period of one electrical scan. Simultaneously, coils C1, C2, C3, and C4 operate. Coil C1 corresponds to coils 21 and 22 in the figure, coil C2 to coils 23 and 24, coil C3 to coils 25 and 26, and coil C4 to coils 27 and 28. The coordinated current flow through these four pairs of coils creates four components of motion perpendicular to the central axis, stimulating an MPI signal. The phase of the AC current flowing through each coil changes clockwise by the same angle Φ (45° for eight drive coils). The currents flowing through them are respectively as follows: Coil 21: Ixy×cos(2×pi×fxy×t), Coil 23: Ixy×cos(2×pi×fxy×t+Φ), Coil 25: Ixy×cos(2×pi×fxy×t+2×Φ), Coil 27: Ixy×cos(2×pi×fxy×t+3×Φ), Coil 22: Ixy×cos(2×pi×fxy×t+4×Φ), Coil 24: Ixy×cos(2×pi×fxy×t+5×Φ), Coil 26: Ixy×cos(2×pi×fxy×t+6×Φ), and Coil 28: Ixy×cos(2×pi×fxy×t+7×Φ). These four pairs of driving coils stimulate magnetic particle signals while driving the FFP to move; under the joint action of the depth coil Cz and the four pairs of coils C1, C2, C3, and C4, the FFP moves both in the depth direction and in the plane perpendicular to the central axis.

[0102] Step S4, receiving the MPI signal based on the receiving coil and sending it to the computer for image reconstruction to form a three-dimensional MPI image;

[0103] In step S4, the received MPI signal is filtered and amplified before being transmitted to a computer, and the concentration distribution of the magnetic nanoparticles along the scanning path in the body of the object is calculated according to the MPI imaging algorithm. Then, data interpolation is used to obtain data of various points on a plane perpendicular to the central axis at a certain depth to obtain a three-dimensional MPI image.

[0104] Step S5, judging whether it is necessary to use a slide rail to perform imaging in a wider range according to the size of the object to be measured and the imaging part; if so, adjusting the position of the slide rail and jumping to step S3 to restart imaging; if it is judged whether it is necessary to change the depth of the point without magnetic field;

[0105] If necessary, the angle adjustment device 4 is used to adjust the tilt angle of the permanent magnet array 1 so that the magnetic field-free point reaches another depth, and the process jumps to step S3 to restart imaging until the depth does not need to be changed, and then the imaging is ended; if not, the imaging is ended directly.

[0106] Among them, see Figure 10 According to the size of the object to be measured, the initial depth of the FFP can be changed by changing the tilt angle of the bar permanent magnet to achieve the purpose of layer selection. At the same time, by adjusting the radius of the ring gear 52 and the gear 51 or the distance between the permanent magnet array 2 and the center of the gear 51, different scanning trajectories such as imaging field of view and scanning density can be obtained.

[0107] As a further explanation of the present invention, a three-dimensional MPI image is formed by image reconstruction, and its specific method includes a system matrix method or an X-space method.

[0108] In the description of the present invention, terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. These are intended solely for ease of description and are not intended to indicate or imply that the device or component described must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not intended to indicate or imply relative importance.

[0109] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0110] The term "comprise" or any other similar term is intended to cover non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0111] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A unilateral magnet rotating magnetic particle imaging device, characterized in that: It comprises a permanent magnet array (1), a horizontal drive coil (2), a depth drive coil (3), a receiving coil, an angle adjustment device (4) and a horizontal movement device (5); The permanent magnet array (1) is used to generate a magnetic field-free point. A horizontal drive coil (2) is arranged in an array inside the permanent magnet array (1). The horizontal drive coil (2) is used to move the magnetic field-free point and excite magnetic particles to generate a nonlinear response signal. A depth drive coil (3) is arranged inside the arrayed horizontal drive coil (2). The depth drive coil (3) is used to generate a uniform magnetic field that changes uniformly and drive the magnetic field-free point to move along the Z-axis direction. The Z-axis direction is the axial direction of the depth drive coil (3). The receiving coil is used to receive magnetic particles to generate a nonlinear response signal; the permanent magnet array (1) is installed in the angle adjustment device (4), and the angle adjustment device (4) is used to adjust the angle of each permanent magnet in the permanent magnet array (1); The horizontal drive coil (2), the depth drive coil (3), the receiving coil and the angle adjustment device (4) are all mounted on a horizontal moving device (5). The horizontal moving device (5) changes the position of the permanent magnet array (1), the horizontal drive coil (2) and the depth drive coil (3), thereby changing the position of the magnetic field-free point on the horizontal plane.

2. The unilateral magnet rotating magnetic particle imaging device according to claim 1, characterized in that: The angle adjustment device (4) comprises a permanent magnet shell (41), a disk (42), a connecting rod (43), a universal joint (44) and a housing (45); Each permanent magnet in the permanent magnet array (1) is respectively installed in a permanent magnet shell (41), one side of the permanent magnet shell (41) is fixed to one end of a connecting rod (43), the other end of the connecting rod (43) is overlapped on the disk (42), and the disk (42) is connected to a driving device, and the driving device is used to drive the disk (42) to move along the Z-axis direction; A universal joint (44) is installed on the other side of the permanent magnet shell (41). The universal joint (44) is arranged in a ball groove and rotates along the ball groove. The ball groove is opened on the inner surface of the outer shell (45).

3. The unilateral magnet rotating magnetic particle imaging device according to claim 2, characterized in that: The driving device includes an end cover (46), a screw hole (47), a screw (48) and a ball seat (49); The end cover (46) is arranged above the housing (45), and a screw hole (47) is provided at the center of the end cover (46). The screw hole (47) is threadedly connected to the screw (48), and the screw (48) is coaxially fixed to the disc (42); A ball seat (49) is installed on the surface of the end cover (46) on the side close to the universal joint (44). The ball seat (49) is installed on the universal joint (44) and is used to limit the range of movement of the universal joint (44).

4. The unilateral magnet rotating magnetic particle imaging device according to claim 1, characterized in that: The horizontal moving device (5) includes a gear (51) and a ring gear (52); A horizontal drive coil (2), a depth drive coil (3), the receiving coil and an angle adjustment device (4) are mounted on the surface of the gear (51). The gear (51) is engaged with a gear ring (52), and the gear ring (52) is mounted on a slide rail of an operating table (6).

5. The unilateral magnet rotating magnetic particle imaging device according to claim 1, characterized in that: The axis of the horizontal drive coil (2) and the axis of the depth drive coil (3) are arranged in parallel.

6. The unilateral magnet rotating magnetic particle imaging device according to claim 3, characterized in that: A universal joint (44) is installed on the other side of the permanent magnet shell (41), and its specific structure is as follows: The other side of the permanent magnet shell (41) is fixed to one end of the connecting block (7), and the other end of the connecting block (7) is fixed to the universal joint (44).

7. The unilateral magnet rotating magnetic particle imaging device according to claim 6, characterized in that: The permanent magnets in the permanent magnet array (1), the permanent magnet shell (41), the connecting rod (43), the connecting block (7), the universal joint (44) and the ball seat (49) are all distributed in a circular array along the axis of the depth drive coil (3).

8. The unilateral magnet rotating magnetic particle imaging device according to claim 7, characterized in that: The number and angle of the annular array distribution of the permanent magnet housing (41), the connecting rod (43), the connecting block (7), the universal joint (44) and the ball seat (49) correspond one-to-one to the number and angle of the annular array distribution of the permanent magnet array (1).

9. A unilateral magnet rotating magnetic particle imaging method, based on the unilateral magnet rotating magnetic particle imaging device according to any one of claims 1 to 8, characterized in that: The method includes: Step S1, placing the object to be measured containing magnetic nanoparticles on the central axis of the device, installing the permanent magnet array (1) into the angle adjustment device (4) based on the position of the object to be measured, and adjusting the tilt angle of the permanent magnet array (1) so that the generated magnetic field-free point is close to the target area in depth; Step S2, installing the angle adjustment device (4), the horizontal drive coil (2), the depth drive coil (3) and the receiving coil in the horizontal moving device (5), and adjusting the size of the imaging field of view by the horizontal moving device (5); Step S3, current is passed through the depth driving coil (3) to make the magnetic field-free point generated by the permanent magnet array (1) move back and forth in the Z-axis direction; at the same time, current is passed through the horizontal driving coil (2) to make the magnetic field-free point move in a horizontal plane perpendicular to the Z-axis, with a motion component perpendicular to the Z-axis, and stimulate the MPI signal; Step S4, receiving the MPI signal based on the receiving coil and sending it to the computer for image reconstruction to form a three-dimensional MPI image; Step S5: Determine whether a slide rail is needed to perform imaging over a wider range based on the size of the object being measured and the imaging location. If so, adjust the slide rail position and jump to step S3 to restart imaging. If not, determine whether the depth of the magnetic field-free point needs to be changed. If necessary, the angle adjustment device (4) is used to adjust the tilt angle of the permanent magnet array (1) so that the magnetic field-free point reaches another depth, and the process jumps to step S3 to restart imaging until the depth does not need to be changed, and then the imaging is ended; if not necessary, the imaging is ended directly.

10. The method for imaging unilateral magnet rotating magnetic particles according to claim 9, characterized in that: A three-dimensional MPI image is formed by image reconstruction, and specific methods thereof include a system matrix method or an X-space method.

Images