High signal-to-noise ratio spatial calibration method and device for magnetic particle imaging

Abstract

The invention belongs to the technical field of magnetic particle imaging, particularly relates to a high signal-to-noise ratio spatial calibration method and device for magnetic particle imaging, and aims to solve the problems of low calibration efficiency and poor spatial calibration precision in the calibration process in the prior art. The method comprises the following steps: gridding imaging view space to generate discrete space points; sequentially positioning the first calibration sample completely filled with the magnetic particle solution and the second calibration sample with the center containing the delta volume filling structure to each space point through a displacement table, and executing ping-pong scanning to obtain a double-sample digital signal; and performing differential processing on the two groups of signals to extract response signals of delta volume magnetic particles, extracting frequency domain harmonic distribution characteristics of the signals, associating the frequency domain harmonic distribution characteristics with space coordinates to construct a matrix vector, and storing the matrix vector until all space points are traversed. According to the method, ping-pong scanning is adopted, background noise is eliminated through double-sample difference, and the signal-to-noise ratio and the overall calibration efficiency are remarkably improved; and meanwhile, the voxel precision of the delta sample after difference is not changed, so that the spatial resolution is ensured.

Description

Background Art

[0002] In magnetic particle imaging (MPI), a periodic alternating magnetic field is used to excite magnetic particles to generate nonlinear response signals, thereby achieving position encoding of magnetic particles in space. However, the real MPI magnetic field is not completely uniform, and it is impossible to obtain accurate real values ​​through magnetic field simulation and numerical calculation. If image reconstruction is performed without calibration, MPI images are bound to have artifacts and distortions. Therefore, it is usually necessary to calibrate the entire imaging field of view space to establish a mapping relationship between the nonlinear response signal and the real magnetic field spatial position.

[0003] Conventional calibration methods usually use a tiny sample (Δ sample) filled with magnetic particles to calibrate the entire imaging field of view. According to the specific designed trajectory, a tiny sample of known concentration is placed at the corresponding position point, and then MPI is turned on for sampling to obtain the response signal of the Δ sample at that point. In the frequency domain, the harmonic distribution of the response signal serves as an identifier of the existence of the spatial position information corresponding to the sample here. Then, the sample is moved to the next position and the same scanning process is repeated until all the position points in the FOV are sampled. Finally, the calibrated harmonic signal matrix will be able to map all spatial positions.

[0004] However, in actual calibration work, there is a contradiction between smaller size and higher signal-to-noise ratio. The size of the Δ sample used for spatial calibration is usually less than 3 mm³, which results in a limited volume of the magnetic particle solution and can only excite very weak nonlinear response signals. As a result, the response signal is difficult to effectively enter the dynamic range of the data acquisition card ADC and is severely interfered by noise.

[0005] There are two technical solutions to solve this problem: 1. Increase the acquisition time of a single pixel spatial point. This method improves the signal-to-noise ratio by sacrificing a lot of time to average the noise, but has poor calibration efficiency.

[0006] 2. Increase the size of the Δ sample to allow more magnetic particles to contribute to the signal, thereby improving the signal-to-noise ratio. However, this method has limited improvement effects. An overly large Δ sample reduces the number of voxels in the calibration matrix, which impairs the accuracy of spatial calibration.

[0007] Based on this, the present invention proposes a high signal-to-noise ratio spatial calibration method and device for magnetic particle imaging. Summary of the invention

[0008] In order to solve the above problems in the prior art, namely, the calibration process of the prior art has low calibration efficiency and poor accuracy of spatial calibration, the present invention provides a high signal-to-noise ratio spatial calibration method for magnetic particle imaging, the method comprising the following steps: Step S1, gridding the imaging field of view of magnetic particle imaging to generate multiple discrete space points; Step S2, moving the first calibration sample and the second calibration sample to each spatial point in turn by means of a translation stage, performing a ping-pong scanning operation, and respectively collecting digital signals of the first calibration sample and the second calibration sample; wherein the first calibration sample is an entity completely filled with a magnetic particle solution, and the second calibration sample is a filled entity with a Δ volume at the center, and the rest of the entity is filled with a magnetic particle solution; Step S3, performing differential processing on the digital signals of the two calibration samples to obtain a response signal contributed by the magnetic particles of volume Δ as a signal to be processed; Step S4, extracting the frequency domain harmonic distribution characteristics of the signal to be processed, combining the position information of the spatial point as a matrix vector, and saving it to a storage medium; Step S5, determining whether all the spatial points have been calibrated; if not, jumping to step S2 and repeating steps S2-S4 until all spatial points have been traversed; if so, the calibration of the imaging field of view is completed.

[0009] Furthermore, the first calibration sample and the second calibration sample are moved to each space point in sequence by the translation stage to perform a ping-pong scanning operation, specifically: Step S21, placing the first calibration sample at the current spatial point, and collecting the digital signal of the first calibration sample; Step S22: Replace the first calibration sample with a second calibration sample at the same spatial point, and collect a digital signal of the second calibration sample.

[0010] Furthermore, the difference between the solution volume of the first calibration sample and the solution volume of the second calibration sample is equal to the volume of the Δ filling entity.

[0011] Furthermore, the first calibration sample and the second calibration sample have the same shape.

[0012] Furthermore, the frequency domain harmonic distribution characteristics of the signal to be processed are extracted by: Perform Fourier transform on the signal to be processed to obtain frequency domain harmonic distribution characteristics.

[0013] In another aspect of the present invention, a high signal-to-noise ratio spatial calibration device for magnetic particle imaging is provided, based on a high signal-to-noise ratio spatial calibration method for magnetic particle imaging, the device comprising: a calibration sample, an MPI scanner, a translation stage, a storage medium and a computer; The calibration samples include 2D calibration samples and 3D calibration samples; The MPI scanner is used to apply a magnetic field during the calibration process to excite the magnetic particles of the calibration sample to generate a nonlinear response signal, and obtain a corresponding digital signal through MPI acquisition; The translation stage is controlled by a computer and is used to move the calibration sample to a gridded spatial point along a preset path; The storage medium is used to store matrix vectors; The computer is communicatively connected with the MPI scanner, the displacement stage and the storage medium.

[0014] Furthermore, the computer is used to control the motion path of the translation stage and the switching of calibration samples, receive the digital signal collected by the MPI scanner and perform differential processing, perform Fourier transform on the differential signal, extract the harmonic distribution characteristics, bind the harmonic distribution characteristics with the spatial point coordinates and store them in a storage medium.

[0015] Furthermore, in the 2D calibration sample, the vertical height inside the sample body is the same as the vertical height of the filling entity of the Δ volume; In the 3D calibration sample, the vertical height inside the sample body is greater than the vertical height of the filling entity of volume Δ, and the filling entity is fixed in the 3D calibration sample by a bracket.

[0016] Furthermore, the shape of the 2D calibration sample at least includes a cuboid, a cylinder or an ellipsoid; The shape of the 3D calibration sample includes at least a cube, a cuboid, a sphere, a cylinder or an ellipsoid, and the shape of the filling entity set in the 3D calibration sample includes a cuboid or a cube.

[0017] Furthermore, the shape of the filling entity provided in the 3D calibration sample includes a cuboid or a cube.

[0018] Beneficial effects of the present invention: (1) By using a larger double calibration sample, the number of magnetic particles involved in signal generation is significantly increased, which greatly improves the response signal strength. At the same time, differential processing is used to eliminate the common environmental noise and background interference in the two samples, effectively suppressing the quantization noise, and significantly improving the signal-to-noise ratio of the net response signal of the target Δ volume, solving the problem of weak signals caused by the small volume of traditional Δ samples.

[0019] (2) Since the volume difference between the first calibration sample and the second calibration sample is strictly equal to the volume of the traditional Δ sample, the equivalent calibration voxel obtained after the difference is consistent with the traditional method, avoiding the problem of reduced voxel number due to excessive sample size. This improves the signal-to-noise ratio while fully retaining the spatial resolution, ensuring that the accuracy of the calibration matrix is ​​not compromised.

[0020] (3) Compared with the traditional single-sample long-time signal averaging method, the present invention uses ping-pong scanning and differential technology to collect two sets of signals in a short time in a single spatial point calibration. Noise suppression can be achieved without extending the single-point acquisition time, which significantly shortens the overall calibration cycle and improves the standard efficiency.

[0021] (4) The calibration device has a simple structure. Dual sample switching and signal acquisition can be achieved through a standard translation stage and an existing MPI scanner without the need for complex hardware modification. At the same time, the flexible design of the 2D / 3D calibration sample can adapt to imaging requirements of different dimensions and is suitable for various MPI systems, with wide versatility and scalability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 is a flow chart of a high signal-to-noise ratio spatial calibration method for magnetic particle imaging of the present invention; Figure 2 It is a schematic diagram of the relationship between calibration samples in a high signal-to-noise ratio spatial calibration method for magnetic particle imaging of the present invention; Figure 3 It is a schematic diagram of the connection relationship of a high signal-to-noise ratio spatial calibration device for magnetic particle imaging of the present invention; Figure 4 It is a schematic diagram of a 2D calibration sample in a high signal-to-noise ratio spatial calibration device for magnetic particle imaging of the present invention; Figure 5 It is a schematic diagram of a 3D calibration sample in a high signal-to-noise ratio spatial calibration device for magnetic particle imaging of the present invention; Figure 6 It is a schematic diagram of a rectangular parallelepiped filling entity in a high signal-to-noise ratio spatial calibration device for magnetic particle imaging of the present invention. DETAILED DESCRIPTION

[0023] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0024] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present 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.

[0025] The present invention provides a high signal-to-noise ratio spatial calibration method for magnetic particle imaging, the method comprising the following steps: Step S1, gridding the imaging field of view of magnetic particle imaging to generate multiple discrete space points; Step S2, moving the first calibration sample and the second calibration sample to each spatial point in turn by means of a translation stage, performing a ping-pong scanning operation, and respectively collecting digital signals of the first calibration sample and the second calibration sample; wherein the first calibration sample is an entity completely filled with a magnetic particle solution, and the second calibration sample is a filled entity with a Δ volume at the center, and the rest of the entity is filled with a magnetic particle solution; Step S3, performing differential processing on the digital signals of the two calibration samples to obtain a response signal contributed by the magnetic particles of volume Δ as a signal to be processed; Step S4, extracting the frequency domain harmonic distribution characteristics of the signal to be processed, combining the position information of the spatial point as a matrix vector, and saving it to a storage medium; Step S5, determining whether all the spatial points have been calibrated; if not, jumping to step S2 and repeating steps S2-S4 until all spatial points have been traversed; if so, the calibration of the imaging field of view is completed.

[0026] The present invention is different from the conventional method of using one sample for calibration. This method requires the use of two calibration samples. Ping-pong scanning is performed on each spatial point (first scanning the first calibration sample, then scanning the second calibration sample) to obtain two sets of independent signals, and then the corresponding harmonic distribution is obtained through computer post-processing and saved in a storage medium. When all spatial positions are calibrated, any spatial point can find a specific harmonic distribution corresponding to it in the saved matrix, and the spatial calibration can be completed.

[0027] In order to more clearly explain the high signal-to-noise ratio spatial calibration method for magnetic particle imaging of the present invention, the following is combined with Figure 1 Each step in the embodiment of the present invention is described in detail.

[0028] A high signal-to-noise ratio spatial calibration method for magnetic particle imaging according to a first embodiment of the present invention includes steps S1 to S5, each of which is described in detail as follows: Step S1, gridding the imaging field of view of magnetic particle imaging to generate multiple discrete space points; In this embodiment, a three-dimensional coordinate system is set according to the maximum imaging range of the magnetic particle imaging device, and a two-dimensional coordinate system or a three-dimensional coordinate system is set according to different experimental requirements. The grid resolution is selected, and the accuracy must be higher than the target imaging resolution to ensure that the calibration covers the tiny structure.

[0029] Step S2, moving the first calibration sample and the second calibration sample to each spatial point in sequence by means of a translation stage, performing a ping-pong scanning operation, and respectively collecting digital signals of the first calibration sample and the second calibration sample; The first calibration sample is a solid body completely filled with a magnetic particle solution, and the second calibration sample is a solid body with a volume of Δ in the center and the rest of the solid body filled with a magnetic particle solution. In this embodiment, two calibration samples are moved to each space point in sequence by a translation stage to perform a ping-pong scanning operation, specifically: Step S21, placing the first calibration sample at the current spatial point, and collecting the digital signal of the first calibration sample; Step S22: Replace the first calibration sample with a second calibration sample at the same spatial point, and collect a digital signal of the second calibration sample.

[0030] Wherein, the digital signal is a time domain response signal.

[0031] Among them, see Figure 2 , the first calibration sample and the second calibration sample have the same shape, and the difference between the solution volume of the first calibration sample and the solution volume of the second calibration sample is equal to the volume of the Δ filling entity.

[0032] Specifically, the first calibration sample and the second calibration sample have the same outer dimensions and a volume greater than 3 mm³, which is several times larger than a conventional Δ sample. The Δ volume filling entity at the center of the second calibration sample is a non-magnetic material that magnetic particles cannot penetrate.

[0033] Step S3, performing differential processing on the digital signals of the two calibration samples to obtain a response signal contributed by the magnetic particles of volume Δ as a signal to be processed; The differential processing is specifically as follows: the digital signal DATA_A corresponding to the first calibration sample and the digital signal DATA_B corresponding to the second calibration sample are aligned in time and then subtracted to obtain a net response signal of the Δ sample.

[0034] Step S4, extracting the frequency domain harmonic distribution characteristics of the signal to be processed, combining the position information of the spatial point as a matrix vector, and saving it to a storage medium.

[0035] In this embodiment, the signal to be processed is transformed using Fourier transform to obtain a frequency domain signal, and the frequency domain harmonic distribution characteristics are obtained through manual screening and analysis.

[0036] Step S5, determining whether all the spatial points have been calibrated; if not, jumping to step S2 and repeating steps S2-S4 until all spatial points have been traversed; if so, the calibration of the imaging field of view is completed.

[0037] The switching path of the spatial points traverses the grid area of ​​the imaging field of view in the order from left to right and from top to bottom. When all the calibrations are completed, the computer controls the MPI scanner, the translation stage, and the storage medium to stop working.

[0038] Although the various steps in the above embodiment are described in the above-mentioned order, those skilled in the art can understand that in order to achieve the effect of this embodiment, different steps do not have to be executed in such an order. They can be executed simultaneously (in parallel) or in a reverse order. These simple changes are within the scope of protection of the present invention.

[0039] See also Figure 3 , a high signal-to-noise ratio spatial calibration device for magnetic particle imaging according to a second embodiment of the present invention, based on a high signal-to-noise ratio spatial calibration method for magnetic particle imaging according to the first embodiment, the device comprises: a calibration sample, an MPI scanner, a translation stage, a storage medium and a computer; The calibration samples include 2D calibration samples and 3D calibration samples; The MPI scanner is used to apply a magnetic field during the calibration process to excite the magnetic particles of the calibration sample to generate a nonlinear response signal, and obtain a corresponding digital signal through MPI acquisition; The translation stage is controlled by a computer and is used to move the calibration sample to a gridded spatial point along a preset path; The storage medium is used to store matrix vectors; The computer is communicatively connected with the MPI scanner, the displacement stage and the storage medium.

[0040] The computer is used to control the motion path of the translation stage and the calibration sample switching, receive the digital signal collected by the MPI scanner and perform differential processing, perform Fourier transform on the differential signal, extract the harmonic distribution characteristics, bind the harmonic distribution characteristics with the spatial point coordinates and store them in a storage medium.

[0041] The calibration sample is fixed on the loading platform of the translation stage, and is driven by the translation stage to move to the target position along the 2D plane or 3D space.

[0042] The computer accurately adjusts the moving path and positioning accuracy of the translation stage through control instructions (such as stepper motor drive signals).

[0043] The computer sends magnetic field excitation instructions to the MPI scanner and receives the time domain response signals (DATA_A and DATA_B) collected by it.

[0044] Computer and storage medium: The computer associates the processed harmonic distribution data with the spatial point coordinates and writes them into the storage medium to construct a calibration matrix.

[0045] The calibration sample is located in the imaging field of the MPI scanner, and its magnetic particle response signal is captured by the receiving coil of the MPI scanner and transmitted to the computer.

[0046] Among them, see Figure 4 and Figure 5 , for the calibration samples, specifically: In the 2D calibration sample, the vertical height inside the sample body is the same as the vertical height of the filling entity of the Δ volume; in other words, the 2D calibration sample is a thin sheet structure suitable for planar imaging calibration; In the 3D calibration sample, the vertical height inside the sample body is greater than the vertical height of the filling entity of the Δ volume, and the filling entity is fixed in the 3D calibration sample by a bracket; in other words, the 3D calibration sample is a thickened cube or cylinder structure, which is suitable for three-dimensional space calibration.

[0047] More specifically, the shape of the 2D calibration sample at least includes but is not limited to a cuboid, a cylinder or an ellipsoid; The shape of the 3D calibration sample includes at least but is not limited to a cube, a cuboid, a sphere, a cylinder or an ellipsoid.

[0048] See also Figure 6 The shape of the filling entity set in the 3D calibration sample includes but is not limited to a cuboid or a cube, and the cuboid is specially used for spatial calibration of MPI without magnetic field lines.

[0049] A third embodiment of the present invention provides a high signal-to-noise ratio spatial calibration system for magnetic particle imaging, based on a high signal-to-noise ratio spatial calibration method for magnetic particle imaging of the first embodiment, the system comprises: A space division module configured to divide the imaging field of view of magnetic particle imaging into grids to generate a plurality of discrete space points; A scanning control module, which is configured to move the first calibration sample and the second calibration sample to each spatial point in sequence through a translation stage, perform a ping-pong scanning operation, and respectively collect digital signals of the first calibration sample and the second calibration sample; wherein the first calibration sample is an entity completely filled with a magnetic particle solution, and the second calibration sample is a filled entity with a Δ volume at the center, and the rest is filled with a magnetic particle solution; A differential processing module is configured to perform differential processing on the digital signals of the two calibration samples to obtain a response signal contributed by the magnetic particles of volume Δ as a signal to be processed; A storage module configured to extract the frequency domain harmonic distribution characteristics of the signal to be processed, combine the position information of the spatial point as a matrix vector, and save it to a storage medium; The judgment module is configured to judge whether all the spatial points have been calibrated; if not, jump to step S2 and repeat steps S2-S4 until all spatial points are traversed; if so, the calibration of the imaging field of view is completed.

[0050] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process and related instructions of the system described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0051] It should be noted that the high signal-to-noise ratio spatial calibration system for magnetic particle imaging provided in the above embodiment is only illustrated by the division of the above functional modules. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the modules or steps in the embodiments of the present invention can be decomposed or combined. For example, the modules in the above embodiment can be combined into one module, or further divided into multiple sub-modules to complete all or part of the functions described above. The names of the modules and steps involved in the embodiments of the present invention are only for distinguishing the modules or steps, and are not regarded as improper limitations of the present invention.

[0052] An electronic device according to a fourth embodiment of the present invention includes: at least one processor; and a memory communicatively connected to at least one of the processors; wherein, The memory stores instructions executable by the processor, and the instructions are used to be executed by the processor to implement the above-mentioned high signal-to-noise ratio spatial calibration method for magnetic particle imaging.

[0053] A fifth embodiment of the present invention is a computer-readable storage medium, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to be executed by the computer to implement the above-mentioned high signal-to-noise ratio spatial calibration method for magnetic particle imaging.

[0054] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process and related instructions of the storage device and processing device described above can refer to the corresponding process in the aforementioned method embodiment and will not be repeated here.

[0055] Those skilled in the art should be able to appreciate that the modules and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented with electronic hardware, computer software, or a combination of the two, and the programs corresponding to the software modules and method steps can be placed in random access memory (RAM), memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium known in the technical field. In order to clearly illustrate the interchangeability of electronic hardware and software, the composition and steps of each example have been generally described in the above description according to the function. Whether these functions are performed in electronic hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0056] The terms "first", "second", etc. are used to distinguish similar objects rather than to describe or indicate a particular order or sequence.

[0057] The term "comprise" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that includes a list of elements includes not only those elements but also other elements not expressly listed, or also includes elements inherent to such process, method, article, or apparatus / device.

[0058] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A high signal-to-noise ratio spatial calibration method for magnetic particle imaging, characterized in that: The method comprises the following steps: Step S1, gridding the imaging field of view of magnetic particle imaging to generate multiple discrete space points; Step S2, moving the first calibration sample and the second calibration sample to each spatial point in turn by means of a translation stage, performing a ping-pong scanning operation, and respectively collecting digital signals of the first calibration sample and the second calibration sample; wherein the first calibration sample is an entity completely filled with a magnetic particle solution, and the second calibration sample is a filled entity with a volume Δ at the center, and the rest of the volume is filled with a magnetic particle solution; Step S3, performing differential processing on the digital signals of the two calibration samples to obtain a response signal contributed by the magnetic particles of volume Δ as a signal to be processed; Step S4, extracting the frequency domain harmonic distribution characteristics of the signal to be processed, combining the position information of the spatial point as a matrix vector, and saving it to a storage medium; Step S5, determining whether all the spatial points have been calibrated; if not, jumping to step S2 and repeating steps S2-S4 until all spatial points have been traversed; if so, the calibration of the imaging field of view is completed.

2. A high signal-to-noise ratio spatial calibration method for magnetic particle imaging according to claim 1, characterized in that: The first calibration sample and the second calibration sample are moved to each space point in sequence by the translation stage to perform a ping-pong scanning operation, specifically: Step S21, placing the first calibration sample at the current spatial point, and collecting the digital signal of the first calibration sample; Step S22: Replace the first calibration sample with a second calibration sample at the same spatial point, and collect a digital signal of the second calibration sample.

3. A high signal-to-noise ratio spatial calibration method for magnetic particle imaging according to claim 1, characterized in that: The difference between the solution volume of the first calibration sample and the solution volume of the second calibration sample is equal to the volume of the Δ filling entity.

4. A high signal-to-noise ratio spatial calibration method for magnetic particle imaging according to claim 1, characterized in that: The first calibration sample and the second calibration sample have the same shape.

5. The high signal-to-noise ratio spatial calibration method for magnetic particle imaging according to claim 1, characterized in that: The frequency domain harmonic distribution characteristics of the signal to be processed are extracted by performing Fourier transform on the signal to be processed to obtain the frequency domain harmonic distribution characteristics.

6. A high signal-to-noise ratio spatial calibration device for magnetic particle imaging, based on a high signal-to-noise ratio spatial calibration method for magnetic particle imaging according to any one of claims 1 to 5, characterized in that: The device comprises: a calibration sample, an MPI scanner, a translation stage, a storage medium and a computer; The calibration samples include 2D calibration samples and 3D calibration samples; The MPI scanner is used to apply a magnetic field during the calibration process to excite the magnetic particles of the calibration sample to generate a nonlinear response signal, and obtain a corresponding digital signal through MPI acquisition; The translation stage is controlled by a computer and is used to move the calibration sample to a gridded spatial point along a preset path; The storage medium is used to store matrix vectors; The computer is communicatively connected with the MPI scanner, the displacement stage and the storage medium.

7. A high signal-to-noise ratio spatial calibration device for magnetic particle imaging according to claim 6, characterized in that: The computer is used to control the motion path of the translation stage and the calibration sample switching, receive the digital signal collected by the MPI scanner and perform differential processing, perform Fourier transform on the differential signal, extract the harmonic distribution characteristics, bind the harmonic distribution characteristics with the spatial point coordinates and store them in a storage medium.

8. The high signal-to-noise ratio spatial calibration device for magnetic particle imaging according to claim 6, characterized in that: In the 2D calibration sample, the vertical height inside the sample body is the same as the vertical height of the filling entity of the Δ volume; In the 3D calibration sample, the vertical height inside the sample body is greater than the vertical height of the filling entity of volume Δ, and the filling entity is fixed in the 3D calibration sample by a bracket.

9. The high signal-to-noise ratio spatial calibration device for magnetic particle imaging according to claim 6, characterized in that: The shape of the 2D calibration sample at least includes a cuboid, a cylinder or an ellipsoid; The shape of the 3D calibration sample at least includes a cube, a cuboid, a sphere, a cylinder or an ellipsoid.

10. The high signal-to-noise ratio spatial calibration device for magnetic particle imaging according to claim 9, characterized in that: The shape of the filling entity set in the 3D calibration sample includes a cuboid or a cube.

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