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

Abstract

The present invention belongs to the technical field of magnetic particle imaging, and particularly relates to a high signal-to-noise ratio spatial calibration method and device for magnetic particle imaging, aiming to solve the problems of low calibration efficiency and poor accuracy of spatial calibration in the existing technology. The present invention includes: dividing the imaging field of view space into a grid to generate discrete spatial points; positioning a first calibration sample completely filled with a magnetic particle solution and a second calibration sample with a Δ-volume filling structure in the center to each spatial point in sequence through a displacement stage, and performing ping-pong scanning to obtain dual-sample digital signals; performing differential processing on the two groups of signals to extract the response signals of the magnetic particles in the Δ volume, extracting the frequency-domain harmonic distribution characteristics of the signals, associating them with the spatial coordinates to construct a matrix vector and storing it until all spatial points are traversed. The present invention adopts ping-pong scanning, eliminates background noise through dual-sample difference, significantly improves the signal-to-noise ratio and overall calibration efficiency; at the same time, the voxel accuracy of the Δ sample remains unchanged after differentiation, ensuring the spatial resolution.

Description

Background Art

[0002] In magnetic particle imaging (MPI), a periodic alternating magnetic field is used to excite magnetic particles to generate a non-linear response signal, thereby realizing position encoding of magnetic particles in space. However, the real MPI magnetic field is not completely uniform, and accurate real values cannot be obtained through magnetic field simulation and numerical calculation. If image reconstruction is performed without calibration, artifacts and distortions are bound to exist in the MPI image. Therefore, it is usually necessary to calibrate the entire imaging field of view space to establish the mapping relationship between the non-linear 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 a designed specific trajectory, a tiny sample with a known concentration is placed at the corresponding position point, and then MPI is started for sampling to obtain the response signal of the Δ sample at this point. In the frequency domain, the harmonic distribution of the response signal serves as the existence identifier 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 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 a smaller size and a higher signal-to-noise ratio. The size of the Δ sample used for spatial calibration is usually below 3 mm³, resulting in a limited volume for filling the magnetic particle solution and only being able to excite a very weak non-linear response signal. 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 existing technical solutions to solve this problem:

[0006] 1. Increase the acquisition time of a single-pixel spatial point. This method sacrifices a large amount of time to average the noise, thereby improving the signal-to-noise ratio, but has poor calibration efficiency.

[0007] 2. Increase the size of the Δ sample to make more magnetic particles contribute signals, thereby improving the signal-to-noise ratio. However, the improvement effect of this method is limited. An overly large Δ sample reduces the number of voxels in the calibration matrix and damages the accuracy of spatial calibration.

[0008] 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

[0009] To solve the above problems in the prior art, that is, the problems of low calibration efficiency and poor accuracy of spatial calibration in the calibration process of the prior art, the present invention provides a high signal-to-noise ratio spatial calibration method for magnetic particle imaging. The method includes the following steps:

[0010] Step S1, grid-divide the imaging field of view space of magnetic particle imaging to generate a plurality of discrete spatial points;

[0011] Step S2, sequentially move the first calibration sample and the second calibration sample to each spatial point through a displacement stage, perform a ping-pong scanning operation, and respectively collect the digital signals of the first calibration sample and the second calibration sample; wherein, the first calibration sample is a solid completely filled with magnetic particle solution, and the second calibration sample is a filled solid with a Δ volume provided in the center, and the rest is filled with magnetic particle solution;

[0012] Step S3, combine the digital signals of the two calibration samples and perform differential processing to obtain the response signal contributed by the magnetic particles with a Δ volume as the signal to be processed;

[0013] Step S4, extract the frequency-domain harmonic distribution characteristics of the signal to be processed, combine the position information of the spatial point where it is located as a matrix vector, and save it to a storage medium;

[0014] Step S5, determine 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, complete the calibration of the imaging field of view.

[0015] Further, sequentially move the first calibration sample and the second calibration sample to each spatial point through a displacement stage and perform a ping-pong scanning operation, specifically:

[0016] Step S21, place the first calibration sample at the current spatial point and collect the digital signal of the first calibration sample;

[0017] Step S22, replace the first calibration sample with the second calibration sample at the same spatial point and collect the digital signal of the second calibration sample.

[0018] Further, 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.

[0019] Further, the first calibration sample and the second calibration sample have the same shape.

[0020] Further, the method for extracting the frequency-domain harmonic distribution characteristics of the signal to be processed is:

[0021] Perform a Fourier transform on the signal to be processed to obtain the frequency-domain harmonic distribution characteristics.

[0022] On the other hand, the present invention proposes 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. The device includes: a calibration sample, an MPI scanner, a displacement stage, a storage medium, and a computer;

[0023] The calibration samples include 2D calibration samples and 3D calibration samples;

[0024] The MPI scanner is used to apply a magnetic field during the calibration process to excite the magnetic particles in the calibration samples to generate non-linear response signals, and the corresponding digital signals are obtained through MPI acquisition;

[0025] The displacement stage is controlled by a computer and is used to move the calibration samples to the grid-like spatial points along a preset path;

[0026] The storage medium is used to store matrix vectors;

[0027] The computer is communicatively connected to the MPI scanner, the displacement stage, and the storage medium.

[0028] Furthermore, the computer is used to control the movement path of the displacement stage and the switching of the calibration samples, receive the digital signals collected by the MPI scanner and perform differential processing, perform Fourier transform on the differentiated signals, extract the harmonic distribution characteristics, bind the harmonic distribution characteristics to the spatial point coordinates, and store them in the storage medium.

[0029] Furthermore, in the 2D calibration sample, the vertical height inside the sample body is the same as the vertical height of the filled entity with a Δ volume;

[0030] In the 3D calibration sample, the vertical height inside the sample body is greater than the vertical height of the filled entity with a Δ volume, and the filled entity is fixed in the 3D calibration sample through a bracket.

[0031] Furthermore, the shape of the 2D calibration sample at least includes a cuboid, a cylinder, or an ellipsoid;

[0032] The shape of the 3D calibration sample at least includes a cube, a cuboid, a sphere, a cylinder, or an ellipsoid, and the shape of the filled entity arranged in the 3D calibration sample includes a cuboid or a cube.

[0033] Furthermore, the shape of the filled entity arranged in the 3D calibration sample includes a cuboid or a cube.

[0034] Advantages of the present invention:

[0035] (1) By adopting relatively large dual calibration samples, the number of magnetic particles participating in signal generation is significantly increased, and the intensity of the response signal is greatly enhanced. At the same time, the common environmental noise and background interference in the two samples are eliminated through differential processing, the quantization noise is effectively suppressed, and the signal-to-noise ratio of the net response signal of the target Δ volume is significantly improved, solving the problem that the signal of the traditional Δ sample is weak due to its too small volume.

[0036] (2) Since the volume difference between the first calibration sample and the second calibration sample is exactly equal to the volume of the traditional Δ sample, the equivalent calibration voxels obtained after differentiation are consistent with the traditional method, avoiding the problem of reduced voxel quantity caused by overly large sample sizes. Thus, while enhancing the signal-to-noise ratio, the spatial resolution ability is completely retained, ensuring that the accuracy of the calibration matrix is not impaired.

[0037] (3) Compared with the traditional method of long-time signal averaging for a single sample, through ping-pong scanning and differentiation techniques, the present invention only requires short-time acquisition of two sets of signals in a single spatial point calibration, achieving noise suppression without extending the single-point acquisition time, significantly shortening the overall calibration cycle, and improving the calibration efficiency.

[0038] (4) The calibration device has a simple structure. The switching between two samples and signal acquisition can be achieved through a standard displacement stage and an existing MPI scanner without complex hardware modification. Meanwhile, the flexible design of 2D / 3D calibration samples can adapt to imaging requirements of different dimensions, is applicable to various MPI systems, and has wide generality and scalability. Description of the Drawings

[0039] By reading the detailed description of the non-restrictive embodiments with reference to the following drawings, other features, objectives, and advantages of this application will become more apparent:

[0040] Figure 1 is a flowchart of a high signal-to-noise ratio spatial calibration method for magnetic particle imaging according to the present invention;

[0041] Figure 2 is a schematic diagram of the relationship of calibration samples in a high signal-to-noise ratio spatial calibration method for magnetic particle imaging according to the present invention;

[0042] Figure 3 is a schematic diagram of the connection relationship of a high signal-to-noise ratio spatial calibration device for magnetic particle imaging according to the present invention;

[0043] Figure 4 is a schematic diagram of a 2D calibration sample in a high signal-to-noise ratio spatial calibration device for magnetic particle imaging according to the present invention;

[0044] Figure 5 is a schematic diagram of a 3D calibration sample in a high signal-to-noise ratio spatial calibration device for magnetic particle imaging according to the present invention;

[0045] Figure 6 is a schematic diagram of a cuboid filled solid in a high signal-to-noise ratio spatial calibration device for magnetic particle imaging according to the present invention. Detailed Embodiments

[0046] The present application will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related invention and are not intended to limit the invention. Additionally, it should be noted that for ease of description, only the parts related to the relevant invention are shown in the drawings.

[0047] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the drawings and embodiments.

[0048] The present invention provides a high signal-to-noise ratio spatial calibration method for magnetic particle imaging, and the method includes the following steps:

[0049] Step S1: Divide the imaging field of view space of magnetic particle imaging into a grid to generate a plurality of discrete spatial points;

[0050] Step S2: Sequentially move the first calibration sample and the second calibration sample to each spatial point through a displacement stage, perform a ping-pong scan operation, and respectively collect the digital signals of the first calibration sample and the second calibration sample; wherein, the first calibration sample is a solid completely filled with a magnetic particle solution, and the second calibration sample is a filled solid with a Δ volume provided at the center, and the rest is filled with a magnetic particle solution;

[0051] Step S3: Combine the digital signals of the two calibration samples and perform differential processing to obtain the response signal contributed by the magnetic particles with a Δ volume as the signal to be processed;

[0052] Step S4: Extract the frequency-domain harmonic distribution characteristics of the signal to be processed, combine the position information of the spatial point where it is located as a matrix vector, and save it to a storage medium;

[0053] Step S5: Determine 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, complete the calibration of the imaging field of view.

[0054] The present invention is different from the conventional calibration using 1 sample. This method requires the cooperation of 2 calibration samples. At each spatial point, a ping-pong scan (first scan the first calibration sample, then scan the second calibration sample) is performed to obtain 2 sets of independent signals, and then the corresponding harmonic distribution is obtained through computer post-processing and saved to 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 thus the spatial calibration can be completed.

[0055] For a clearer description of a high signal-to-noise ratio spatial calibration method for magnetic particle imaging according to the present invention, the following combines Figure 1 Details of each step in the embodiments of the present invention are elaborated.

[0056] A high signal-to-noise ratio spatial calibration method for magnetic particle imaging according to the first embodiment of the present invention includes steps S1 - S5, and each step is described in detail as follows:

[0057] Step S1: Divide the imaging field of view space of magnetic particle imaging into a grid to generate a plurality of discrete spatial points;

[0058] In this embodiment, according to the maximum imaging range of the magnetic particle imaging device, a three-dimensional coordinate system is set, and according to different experimental requirements, a two-dimensional coordinate system or a three-dimensional coordinate system is set. Select the grid resolution, and the accuracy should be higher than the target imaging resolution to ensure that the calibration covers the microstructures.

[0059] Step S2: Move the first calibration sample and the second calibration sample to each spatial point in turn through a displacement stage, perform a ping-pong scanning operation, and respectively collect the digital signals of the first calibration sample and the second calibration sample;

[0060] Among them, the first calibration sample is a solid completely filled with magnetic particle solution, and the second calibration sample is a filled solid with a Δ volume in the center, and the rest is filled with magnetic particle solution;

[0061] In this embodiment, moving the two calibration samples to each spatial point in turn through a displacement stage and performing a ping-pong scanning operation specifically means:

[0062] Step S21: Place the first calibration sample at the current spatial point and collect the digital signal of the first calibration sample;

[0063] Step S22: Replace the first calibration sample with the second calibration sample at the same spatial point and collect the digital signal of the second calibration sample.

[0064] Among them, the digital signal is a time-domain response signal.

[0065] Among them, referring to 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.

[0066] Specifically, the first calibration sample and the second calibration sample have the same external dimensions and the volume is greater than 3 mm³, which is several times larger than the conventional Δ sample, and the Δ volume filling entity in the center of the second calibration sample is a non-magnetic material that magnetic particles cannot penetrate.

[0067] Step S3: Combine the digital signals of the two calibration samples and perform differential processing to obtain the response signal contributed by the magnetic particles with a Δ volume as the signal to be processed;

[0068] 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 the net response signal of the Δ sample.

[0069] Step S4: Extract the frequency-domain harmonic distribution characteristics of the signal to be processed, combine the position information of the spatial point where it is located as a matrix vector, and save it to the storage medium.

[0070] In this embodiment, the signal to be processed is subjected to Fourier transform to obtain a frequency-domain signal, and the frequency-domain harmonic distribution characteristics are obtained through manual screening and analysis.

[0071] Step S5: Determine 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.

[0072] Among them, 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 displacement stage, and the storage medium to stop working.

[0073] In the above embodiments, although the various steps are described in the above order, those skilled in the art can understand that in order to achieve the effects of this embodiment, different steps do not have to be executed in such an order, and they can be executed simultaneously (in parallel) or in a reversed order, and these simple changes are all within the protection scope of the present invention.

[0074] See Figure 3 , a high signal-to-noise ratio spatial calibration device for magnetic particle imaging according to the 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 includes: a calibration sample, an MPI scanner, a displacement stage, a storage medium, and a computer;

[0075] The calibration sample includes a 2D calibration sample and a 3D calibration sample;

[0076] 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 non-linear response signal, and the corresponding digital signal is obtained through MPI acquisition;

[0077] The displacement stage is controlled by the computer and is used to move the calibration sample to the grid-shaped spatial points along a preset path;

[0078] The storage medium is used to store the matrix vector;

[0079] The computer is communicatively connected to the MPI scanner, the displacement stage, and the storage medium.

[0080] The computer is used to control the movement path of the displacement stage, calibrate sample switching, receive digital signals collected by the MPI scanner and perform differential processing, perform Fourier transform on the differential signals, extract harmonic distribution characteristics, bind the harmonic distribution characteristics with spatial point coordinates and store them in a storage medium.

[0081] Among them, the calibration sample is fixed on the carrier platform of the displacement stage and is driven by the displacement stage to move to the target position point along a 2D plane or 3D space.

[0082] The computer precisely adjusts the movement path and positioning accuracy of the displacement stage through control instructions (such as stepper motor drive signals).

[0083] The computer sends a magnetic field excitation instruction to the MPI scanner and receives the time-domain response signals (DATA_A and DATA_B) collected by it.

[0084] Computer and storage medium: The computer associates the processed harmonic distribution data with spatial point coordinates and writes them into the storage medium to construct a calibration matrix.

[0085] The calibration sample is located within the imaging field of view 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.

[0086] Among them, referring to Figure 4 and Figure 5 , for the calibration sample, specifically:

[0087] In the 2D calibration sample, the vertical height inside the sample body is the same as the vertical height of the filled entity with Δ volume; in other words, the 2D calibration sample is a thin and light sheet-like structure, suitable for planar imaging calibration;

[0088] In the 3D calibration sample, the vertical height inside the sample body is greater than the vertical height of the filled entity with Δ volume, and the filled entity is fixed inside the 3D calibration sample through a bracket; in other words, the 3D calibration sample is a thickened cube or cylinder structure, suitable for three-dimensional space calibration.

[0089] More specifically, the shape of the 2D calibration sample includes at least but is not limited to a cuboid, a cylinder or an ellipsoid;

[0090] 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.

[0091] Referring to Figure 6 , the shape of the filled entity arranged in the 3D calibration sample includes but is not limited to a cuboid or a cube, and the cuboid is specifically used for spatial calibration of MPI without magnetic field lines.

[0092] The 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 in the first embodiment. The system includes:

[0093] A spatial division module configured to divide the imaging field of view space of magnetic particle imaging into a grid, generating a plurality of discrete spatial points;

[0094] A scanning control module configured to sequentially move a first calibration sample and a second calibration sample to each spatial point through a displacement 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 a solid completely filled with a magnetic particle solution, and the second calibration sample is a filled solid with a Δ volume provided at the center, and the rest is filled with a magnetic particle solution;

[0095] A differential processing module configured to perform differential processing on the digital signals of the two calibration samples to obtain a response signal contributed by the magnetic particles in the Δ volume as a signal to be processed;

[0096] 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 where it is located as a matrix vector, and save it to a storage medium;

[0097] A judgment module 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, complete the calibration of the imaging field of view.

[0098] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working process and related explanations of the above-described system can refer to the corresponding process in the foregoing method embodiment, and will not be repeated here.

[0099] 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 dividing the above-mentioned functional modules. In actual applications, the above functions can be allocated to different functional modules as needed, that is, the modules or steps in the embodiments of the present invention can be further decomposed or combined. For example, the modules in the above embodiment can be combined into one module, or further split into multiple sub-modules to complete all or part of the functions described above. For the names of the modules and steps involved in the embodiments of the present invention, they are only used to distinguish each module or step, and are not regarded as an improper limitation of the present invention.

[0100] An electronic device according to the fourth embodiment of the present invention includes:

[0101] At least one processor; and

[0102] A memory communicatively connected to at least one of the processors; wherein,

[0103] 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.

[0104] A computer-readable storage medium according to the fifth embodiment of the present invention, 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.

[0105] Those skilled in the art can clearly understand that for the convenience and conciseness of description, the specific working processes and related descriptions of the above-described storage device and processing device can refer to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0106] Those skilled in the art should be able to realize that the modules and method steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. The programs corresponding to the software modules and method steps can be placed in a random access memory (RAM), memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium well-known in the art. For the sake of clearly illustrating the interchangeability of electronic hardware and software, the components and steps of each example have been generally described according to their functions in the above description. Whether these functions are executed in the form of 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.

[0107] Terms such as "first", "second", etc. are used to distinguish similar objects, rather than to describe or represent a specific order or sequence.

[0108] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, so that a process, method, article, or device / equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent in these processes, methods, articles, or devices / equipment.

[0109] So far, the technical solution of the present invention has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easily understood by those skilled in the art 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 all 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 includes the following steps: Step S1: Divide the imaging field of view space of magnetic particle imaging into a grid to generate a plurality of discrete spatial points; Step S2: Sequentially move the first calibration sample and the second calibration sample to each spatial point through a displacement stage, perform a ping-pong scanning operation, and respectively collect the digital signals of the first calibration sample and the second calibration sample; wherein, the first calibration sample is a solid completely filled with magnetic particle solution, and the second calibration sample is a filled solid with a Δ volume provided at the center, and the rest is filled with magnetic particle solution; Step S3: Combine the digital signals of the two calibration samples and perform differential processing to obtain the response signal contributed by the magnetic particles with a Δ volume, which is used as the signal to be processed; Step S4: Extract the frequency-domain harmonic distribution characteristics of the signal to be processed, combine the position information of the spatial point where it is located as a matrix vector, and save it to a storage medium; Step S5: Determine 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, complete the calibration of the imaging field of view.

2. The high signal-to-noise ratio spatial calibration method for magnetic particle imaging according to claim 1, wherein Sequentially move the first calibration sample and the second calibration sample to each spatial point through a displacement stage and perform a ping-pong scanning operation, specifically: Step S21: Place the first calibration sample at the current spatial point and collect the digital signal of the first calibration sample; Step S22: Replace the first calibration sample with the second calibration sample at the same spatial point and collect the 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 filled solid.

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

5. A high signal-to-noise ratio spatial calibration method for magnetic particle imaging according to claim 1, characterized in that The method for extracting the frequency-domain harmonic distribution characteristics of the signal to be processed is: perform a 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 the high signal-to-noise ratio spatial calibration method for magnetic particle imaging according to any one of claims 1-5, characterized in that, The device includes: a calibration sample, an MPI scanner, a displacement stage, a storage medium, and a computer; The calibration sample includes a 2D calibration sample and a 3D calibration sample; The MPI scanner is used to apply a magnetic field during the calibration process, excite the magnetic particles of the calibration sample to generate a non-linear response signal, and obtain the corresponding digital signal through MPI acquisition; The displacement stage is controlled by the computer and is used to move the calibration sample to the grid-like spatial points along a preset path; The storage medium is used to store the matrix vector; The computer is communicatively connected to 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 movement path of the displacement stage and the switching of the calibration sample, receive the digital signals collected by the MPI scanner and perform differential processing, perform a 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 the storage medium.

8. A 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 filled solid with a Δ volume; In the 3D calibration sample, the vertical height inside the sample body is greater than the vertical height of the filled solid with a Δ volume, and the filled solid is fixed inside the 3D calibration sample through a bracket; 9. A 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 includes at least 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.

10. A 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 arranged in the 3D calibration sample includes a cuboid or a cube.

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