88 results about "Magnetic particle imaging" patented technology

The invention provides a magnetic particle imaging resolution improving method and system based on frequency domain information filtering, and relates to the technical field of magnetic particle imaging. Comprising the following steps: inputting original magnetic particle imaging data into a Transform model, and selectively filtering frequency domain information in the magnetic particle imaging data through a fusion frequency domain discrimination feedforward network module in an encoder to obtain the output of the encoder; inputting the output of the encoder into a bottleneck layer, aggregating global and local information through a multi-scale attention mechanism module, and then selectively filtering frequency domain information in the magnetic particle imaging data again to obtain the output of the bottleneck layer; inputting the output of the bottleneck layer into a decoder with the same structure as the bottleneck layer to obtain deep features; inputting the deep features into a convolutional layer to obtain a residual image; and calculating the sum of the original magnetic particle imaging data and the residual image to obtain a reconstructed image. According to the invention, the overall imaging resolution of the MPI image under the low-gradient field acquisition condition is improved.

The invention belongs to the field of image reconstruction of magnetic particle imaging and multi-modal generative artificial intelligence models, particularly relates to a magnetic particle image reconstruction method and system based on a multi-modal diffusion model, and aims to solve the problem that there is no method capable of combining a generative model and a multi-modal imaging technology to realize accurate quantitative reconstruction of MPI. The method comprises the following steps: carrying out integral modeling and discretization operation on a first excitation signal to obtain discrete signals, fitting and superposing the discrete signals to obtain a first response signal, calculating a loss function, and training a model based on the loss function; processing the second time sequence signal by using the trained particle response model to obtain a second response signal; calculating based on the second response signal and the system matrix, gradually adding noise, and constraining to obtain a noise constrained image; and gradually denoising and recovering the noise constraint image in the last step to obtain a final reconstructed image. According to the invention, rapid and high-quality MPI image reconstruction becomes possible.

The invention relates to the technical field of biological medicine, in particular to a diagnosis and treatment integrated brain-targeted magnetic particle imaging tracer and a preparation method and application thereof. The preparation method comprises the following steps: loading tetrahydrocurcumin into glucan by adopting a nano-particle self-assembly technology to form glucan nano-particles loaded with tetrahydrocurcumin, synthesizing Fe3O4 nano-particles by adopting a chemical precipitation method, and embedding the Fe3O4 nano-particles on the glucan nano-particles to obtain the diagnosis and treatment integrated brain-targeted magnetic particle imaging tracer agent. The nano-particles are marked as THC (at) Dex-Fe3O4 nano-particles. The THC-Dex-Fe3O4 nanoparticles play a role in treating the Alzheimer's disease during brain imaging diagnosis, and the technical problems that magnetic particle imaging cannot be applied to diagnosis of the Alzheimer's disease and the Alzheimer's disease is difficult to treat are solved.

The invention relates to the technical field of medical imaging, in particular to a narrowband-based multi-harmonic magnetic particle imaging method, which comprises the following steps of: determining a magnetic particle imaging area, and acquiring a first area and a second area according to the magnetic particle imaging area; placing a magnetic nanoparticle sample in the first area, externally applying a magnetic field, and extracting harmonic signals to construct a system matrix; placing a measured object in the second area and externally applying a magnetic field, and extracting harmonic signals to construct a harmonic signal matrix of the measured object; and according to the system matrix and the harmonic signal matrix of the measured object, constructing an equation to be solved and carrying out inversion solution to obtain an image of magnetic nanoparticle concentration distribution. Compared with a broadband imaging technology, the narrow-band imaging technology is adopted, the requirement for the bandwidth of a magnetic particle imaging system is lowered, and the problem of insufficient bandwidth under high-frequency excitation is solved.

The invention belongs to the technical field of magnetic particle imaging, relates to a magnetic particle imaging reconstruction method based on multi-angle Cartesian scanning adaptive optimization, and aims to solve the problems of easy information redundancy, low resolution and insufficient response signal representation under the condition of low gradient in free point scanning in the existing imaging technology. The method comprises the following steps: setting magnetic field generation related parameters and a measurement mode of a rotating Cartesian angle scanning track of a magnetic field free point; constructing a system function harmonic diagram under each rotation angle; constructing a system matrix under each rotation angle, analyzing the system matrix under each angle and the weight and contribution of each frequency component in the system matrix, and determining an optimal system matrix; constructing an observation vector sequence; and reconstructing a magnetic particle image. According to the method, image reconstruction is carried out through the Cartesian scanning track of the free point of the rotating magnetic field and the weighted multi-angle system matrix, the system matrix and particle response representation under the low gradient are enriched, and the imaging resolution is improved.

The present application relates to the field of magnetic particle imaging, and particularly relates to a kind of fast calibration method and system of MPI system matrix based on multi-stage wavelet transform and double branch attention network, to solve the problem of time-consuming, complex of existing calibration-based system matrix acquisition method.The method of the present application comprises: obtaining a low-resolution system matrix according to a pre-set undersampling grid;The system matrix is encoded by row RGB to obtain an RGB image;The above-mentioned RGB image is input into the trained MWaveDAN network model to obtain a high-resolution RGB image;The high-resolution RGB image is decoded into complex form to obtain a complex-based system matrix.The present application effectively accelerates the high-resolution acquisition of system matrix in MPI, and provides important support for the future development of MPI technology.

A processor calculates a system function by a first deconvolution operation based on a set of a first detection signal obtained while a calibration sample is disposed in an examination region and a numerical model of a spatial distribution of magnetic particles included in the calibration sample. The processor obtains a spatial distribution of magnetic particles included in an examination sample by a second deconvolution operation based on a set of a second detection signal obtained while the examination sample is disposed in the examination region and the system function.

The invention relates to the technical field of magnetic particle imaging, in particular to a core-shell nanoprobe and a preparation method and application thereof.The core-shell nanoprobe comprises a magnetic core and a nanoshell which is located outside the magnetic core and has a magnetic shielding response function, and the structure of the nanoshell collapses under the tumor microenvironment condition; the saturation magnetization of the magnetic core is greater than or equal to 50 emu / g, and the coercive force is less than or equal to 5 Oe; the saturation magnetization of the nano shell is less than 50 emu / g, and the coercive force is more than 5 Oe. According to the core-shell nanoprobe, through a unique magnetic core-shell structure design and tumor microenvironment response characteristics, a magnetic shielding layer is formed by using a low-signal nano shell with a response magnetic shielding function, and background signal interference is inhibited. In a tumor microenvironment, the shell structure of the core-shell nanoprobe collapses, the magnetic core is exposed, and a high magnetic signal is released and generated, so that the imaging signal-to-noise ratio is remarkably improved. According to the invention, the bottleneck that the traditional MPI probe is lighted in the whole course can be broken through, the tumor specificity is lighted and positioned, and the problems that the external background of the tumor is high, the contrast ratio is poor, and tiny focuses are difficult to detect are solved.

The invention discloses a magnetic particle imaging method based on multi-harmonic energy-full width at half maximum combined weighting, which comprises the following steps: acquiring point spread functions of a plurality of harmonic waves with different frequencies of magnetic nanoparticles, and constructing a corresponding system matrix; measuring a reference sample which does not contain the magnetic nanoparticles, and obtaining a plurality of noise matrixes corresponding to harmonic waves with different frequencies; measuring the sample to be measured, and obtaining magnetization response voltage vectors of a plurality of harmonic waves with different frequencies; respectively calculating an energy two-norm of a system matrix, an energy two-norm of a noise matrix and a full width at half maximum of a point spread function of the system matrix and the noise matrix; splicing the magnetization response voltage signals of each harmonic system matrix to form a total system matrix and a total measurement signal vector; calculating a weight factor of each harmonic wave and forming a weight matrix; and constructing a solution equation of the particle concentration distribution of the sample to be detected, and carrying out iterative solution on the solution equation to obtain a particle concentration distribution image of the sample to be detected. According to the invention, efficient utilization of multi-harmonic information is realized.

A magnetic particle imaging device is provided with: a detection coil (3) for detecting a magnetic change in magnetic particles (1); a compensation coil (4) having a central axis (CA) common to the detection coil (3) and connected to the detection coil (3) with opposite polarity; a first winding tube (21) that holds the detection coil (3); and a second winding tube (22) that holds the compensation coil (4). The distance in the direction of the central axis (CA) of the detection coil (3) and the compensation coil (4) can be changed by increasing or decreasing the contact portion of the first winding tube (21) and the second winding tube (22).

A magnet (100, 300, 400) for a magnetic particle imaging device is provided with a pair of first DC coils (10), a pair of second DC coils (20), and a pair of AC coils (30). The pair of first DC coils are disposed facing each other in a first direction (DR1). The pair of second DC coils are disposed facing each other in a second direction (DR2) perpendicular to the first direction or in a third direction (DR3) perpendicular to the first direction and the second direction. The pair of AC coils is disposed facing each other in a first direction or a second direction. Each of the pair of second DC coils has a pair of first linear portions (22). Each of the pair of first linear portions extends in the same direction as the direction in which the pair of AC coils are disposed facing each other.

The present invention belongs to the field of magnetic particle imaging, specifically to a generative reconstruction method for magnetic particle imaging based on physical priors. This method aims to address the issues of long matrix calibration time for magnetic particle imaging systems, reliance on model assumptions in mathematical modeling methods, and difficulty balancing acceleration performance and recovery accuracy in acceleration-based calibration methods, which in turn lead to low accuracy in reconstructed MPI images. The method comprises: constructing a system matrix containing physical priors; splitting the system matrix by column to obtain a set of system matrix columns as the original system matrix columns; inputting the original system matrix columns and various physical priors into a potential diffusion model based on physical priors for fine-tuning and training; inputting newly measured physical priors into the trained model to obtain generated system matrix columns, thereby forming a complete system matrix. The method then combines the measured signals to solve ill-conditioned equations and obtain an MPI image of the object to be measured. The present invention improves the accuracy of MPI image reconstruction while eliminating the need to calibrate the system matrix.

The present invention belongs to the field of magnetic particle imaging technology, and specifically relates to a magnetic particle imaging system and method based on a flexible receiving coil array, which aims to solve the problems of poor adaptability of current rigid receiving coils to biological surfaces and low signal-to-noise ratio for imaging tiny geometric textures. The present invention: Structurally, the receiving coil array is adhered to the surface of the object to be measured, and the compensation coil array is distributed on both sides of the flexible substrate. The receiving coil array is used to receive magnetic nanoparticle signals, and the block-type small compensation coil array is used to compensate for feedthrough interference and electromagnetic interference of the receiving coil; in terms of reconstruction method, the collected receiving signal is Fourier transformed in sequence, the in-phase third harmonic is extracted and superimposed to obtain the processed signal, interpolation is used to construct a sinusoidal diagram for the Cartesian coordinate distribution, and the filtered back projection method is used to reconstruct the three-dimensional particle concentration distribution of the object to be measured. The present invention adopts a flexible receiving coil array strategy and provides an adaptive reconstruction method, thereby improving the imaging signal-to-noise ratio.

The application discloses a kind of HPLC pipeline blockage detection system and method based on magnetic particle imaging, solve the problem that traditional indirect measurement mode relies on the experience and ability of instrument user, it is difficult to accurately identify the position and degree of blockage, low efficiency, easy to cause instrument damage.The HPLC pipeline blockage detection system and method based on magnetic particle imaging inject mobile phase containing magnetic nanoparticles into HPLC pipeline, open the flow pressure pump of HPLC to make liquid flow, then excite magnetic nanoparticles in the field-free point (FFP) of gradient field by alternating magnetic field, and use detection coil to induct the signal generated by magnetic nanoparticles, then transmit to data processing system, complete the detection of blockage position information in HPLC pipeline.The detection system and method realize real-time, non-destructive detection of HPLC pipeline blockage by the magnetic response characteristics of magnetic nanoparticles under the action of external magnetic field, can improve the accuracy and stability of analysis result, wide application range.

The application relates to the field of magnetic particle imaging, in particular to a magnetic nanoparticle imaging system based on a permanent magnet and electromagnet composite driving mode, which comprises a magnet device, a first electric rotating table, a second electric rotating table, a third electric rotating table and a sample feeding device, the first electric rotating table and the second electric rotating table are located on the two sides of the magnet device, the third electric rotating table is located on one side of the second electric rotating table, the magnet device comprises a permanent magnet and an electromagnet, the permanent magnet comprises a focusing field permanent magnet and two selection field permanent magnets, the two selection field permanent magnets are driven to rotate through the first electric rotating table and the second electric rotating table, the focusing field permanent magnet is driven to rotate through the third electric rotating table, the electromagnet part is located outside the permanent magnet part and does not rotate, and the sample feeding device is located in the cavity of the permanent magnet part and does not rotate. The permanent magnet and the electromagnet composite driving mode can effectively reduce the power consumption of the magnetic nanoparticle imaging system.

The application belongs to the field of magnetic particle imaging, and particularly relates to a rotating gradient magnetic particle imaging device and method based on cross-coil driving, aiming to solve the problems of difficulty in effective coding in the absence of a magnetic field region and low imaging sensitivity in magnetic particle imaging. The application comprises: superimposing the magnetic field generated by two pairs of mutually orthogonal cross-coil pairs and the uniform bias field through a magnetic field generation module to generate an imaging region magnetic field; changing the current direction of any one of the coil pairs in the cross-coil pair or changing the current type of the cross-coil pair to generate a rotating magnetic field under multiple rotating gradients through a gradient rotating module while the uniform bias field remains unchanged; obtaining scanning signals of each point in the imaging region under different magnetic fields through a scanning module; and generating the imaging result of the object to be measured based on the scanning signals under different magnetic fields through an imaging module. The application can realize high-sensitivity and reliable two-dimensional position coding MPI imaging without relying on the traditional magnetic field-free region.

The invention belongs to the field of magnetic particle imaging, particularly relates to a rapid system matrix calibration algorithm applied to magnetic particle imaging, and aims to solve the problem that rapid system matrix calibration and high-resolution imaging cannot be considered at the same time in the prior art. The method comprises the following steps: acquiring a public data set, screening a high signal-to-noise ratio system matrix, converting the matrix into a three-dimensional cube format, and dividing the matrix into a training set and a test set according to scanning parameters; the method comprises the following steps: acquiring frequency domain response of a magnetic nanoparticle point-like phantom in a scanning / excitation magnetic field through actual measurement, and generating an actual measurement system matrix set through mobile sampling and frequency point screening; constructing a magnetic particle concentration distribution matrix, and generating a simulation system matrix set through numerical simulation and frequency point screening; constructing a deep learning model which comprises an image coding unit, a feature processing unit and an image reconstruction unit; and inputting the matrix to be calibrated into the trained model, and outputting the calibrated high-resolution system matrix. According to the method, the calibration efficiency is remarkably improved, and the imaging resolution is maintained.

This invention belongs to the field of magnetic particle imaging, specifically relating to a three-dimensional magnetic particle imaging system, method, and device that fuses imaging parameters for quantitative analysis. It aims to address the problem that existing technologies only focus on the quality analysis of two-dimensional MPI reconstructed images, using a single parameter and failing to comprehensively assess the combined influence of multiple factors on the reconstructed image, resulting in poor quality of the reconstructed MPI three-dimensional image. The system includes: an input module configured to acquire a phantom model of the object to be reconstructed, as well as the imaging parameters and interference parameters of the MPI imaging device; a signal calculation module configured to calculate the induced voltage signal; a reconstruction module configured to perform three-dimensional reconstruction of the object to be imaged based on the induced voltage signal using a three-dimensional image reconstruction method to obtain an MPI three-dimensional reconstructed image; and an output module configured to output the MPI three-dimensional reconstructed image. This invention improves the quality of MPI three-dimensional reconstructed images.

The present application belongs to the technical field of magnetic particle imaging, and particularly relates to an open magnetic particle imaging method and system based on magnetic field rotation coding, aiming to solve the problems of limited imaging resolution, insufficient imaging depth, excessive power consumption and the inability of MPS to image in the prior art single-sided MPI imaging. The present application: uses a bar-shaped permanent magnet or a coil to create a stable and controllable static magnetic field environment, drives the static magnetic field to rotate by means of a mechanical mechanism, changes the distribution form of the spatial static magnetic field and completes the coding operation, increases the number of independent equations to be solved, and then generates a system matrix, constructs a matrix equation capable of accurately solving the magnetic particle concentration distribution, solves the matrix equation, and successfully reconstructs the magnetic particle image of the target object. The present application is applied to a single-sided MPI device, effectively increases the imaging depth, improves the resolution and reduces the power consumption; and is applied to an MPS device, has imaging capability and expands the application range.

The present application belongs to the field of magnetic particle imaging, and particularly relates to a magnetic particle imaging image reconstruction method, system and device based on a max-min concave and total variation constraint, aiming to solve the problem of large error, poor precision and low quality of the MPI image reconstructed by the existing magnetic particle imaging image reconstruction method. The method comprises: acquiring a time domain voltage signal as an input signal; performing Fourier transform on the input signal and constructing a system matrix; based on the system matrix, constructing a mapping equation between the concentration of magnetic particle imaging and the input signal after Fourier transform as a first equation; combining isotropic total variation and max-min concave constraint to reconstruct the first equation to obtain a second equation; and iteratively solving the second equation by an alternating direction multiplier method with a mixed penalty function to obtain the concentration of magnetic particle imaging and perform image reconstruction. The present application reduces the error of the reconstructed MPI image, and improves the precision and quality of the reconstructed MPI image.

The invention belongs to the field of medical image reconstruction, particularly relates to a projection type magnetic particle imaging sparse view angle reconstruction method, system and equipment, and aims to solve the problem of insufficient accuracy of a sparse view angle reconstruction technology. The method comprises the following steps: acquiring three-dimensional projection data of a to-be-imaged target at a sampling projection angle; segmenting the three-dimensional projection data into a plurality of plane slices, and obtaining a space coordinate vector and a sampling projection angle of any plane slice; generating input data based on the neighborhood set of the sampling projection angle of each plane slice, the space coordinate vector and the sampling projection angle, and constructing a projection completion network by taking the magnetic particle concentration signal as output data; optimizing the projection completion network by obtaining an uncertainty index; generating a complementation projection based on the optimized projection complementation network; and performing back projection reconstruction on the complemented projection to obtain a reconstructed image of the to-be-imaged target. According to the invention, high-accuracy magnetic particle imaging can be realized through less data.

The application belongs to the field of magnetic particle imaging, and particularly relates to a magnetic particle imaging method and device based on multi-source noise monitoring and collaborative compensation, aiming to solve the problem that magnetic particle signals are easily interfered by multi-source noise. The method comprises the following steps: during excitation or gradient field operation, a main receiving signal is collected, and multi-path noise monitoring signals are synchronously collected through at least two noise monitoring coils; the multi-path noise monitoring signals are input into a background noise prediction model to obtain predicted background noise, wherein the background noise prediction model is trained based on signals collected by the main receiving coil and the noise monitoring coil under the no-load state of a magnetic particle imaging device; the predicted background noise is eliminated from the main receiving signal to obtain a purified magnetic particle response signal; and a reconstructed image is generated based on the purified magnetic particle response signal. The application can obtain a high signal-to-noise ratio MPI response signal online, and improve the imaging speed and long-term stability without changing the existing scanning architecture.

The application provides a kind of multi-block magnetic particle imaging method and system, which can be applied to medical image processing technical field.The method comprises the following steps: collecting a plurality of magnetic particle system matrices corresponding to a plurality of sub-imaging regions in the region to be imaged respectively; using a trained boundary prediction model to perform extrapolation on the plurality of magnetic particle system matrices to obtain a plurality of matrix extrapolated magnetic particle system matrices, the trained boundary prediction model being trained using simulation-generated magnetic particle system matrix samples and a loss function based on spatial continuity constraints and edge sparsity constraints; using the plurality of matrix extrapolated magnetic particle system matrices to perform image reconstruction on the plurality of sub-imaging regions to obtain a plurality of field-of-view expanded magnetic particle image blocks; performing cropping on the plurality of field-of-view expanded magnetic particle image blocks to obtain a plurality of boundary artifact-eliminated magnetic particle image blocks; and splicing the plurality of boundary artifact-eliminated magnetic particle image blocks to obtain a magnetic particle imaging result of the region to be imaged.

The present application relates to the vertical magnetization-based isotropic X-space magnetic particle imaging device and method, the imaging device includes scanning coil, excitation coil and vertical receiving coil, the magnetic particle in the magnetic field-free region generates the magnetic particle signal under the excitation of excitation coil magnetic field, and the vertical receiving coil receives the vertical magnetization response signal;Scanning coil drives the magnetic field-free region to traverse the imaging plane region where the object to be imaged is located, then determines the scanning track grid according to the scanning coil current, compensates according to the excitation coil current, obtains the initial image containing the corresponding relationship between the instantaneous signal and the track grid position, and reconstructs the initial image to obtain the isotropic concentration distribution image of the object to be imaged.The present application only uses a pair of mutually perpendicular excitation-receiving coils, solves the direct coupling problem of the MPI device, simultaneously utilizes the vertical magnetization signal combined with the improved X-space reconstruction method, realizes the isotropic reconstruction and real-time reconstruction.

The present invention provides a rapid single harmonic magnetic particle imaging device and method based on perpendicular magnetization. This device uses orthogonal sensing coils instead of single receiving coils to acquire multidimensional single harmonic magnetic particle signals for joint reconstruction, achieving full electromagnetic scanning. Therefore, while improving the quality of single harmonic magnetic particle images, the present invention facilitates rapid imaging of single harmonic MPI, alleviates the problem of inaccurate reconstructed images caused by the mutual cancellation of certain harmonic signals, and can improve image reconstruction quality under single harmonic reconstruction. Compared with traditional single harmonic magnetic particle imaging methods, the present invention achieves full electromagnetic scanning, which facilitates rapid single harmonic magnetic particle imaging; and effectively utilizes perpendicular magnetization signals to achieve accurate imaging.

The forward model constrained neural network magnetic particle imaging reconstruction method disclosed by the application obtains a system matrix through calibration, measures voltage data generated by a sample; Fourier transforms the collected data into a frequency domain, uses a signal-to-noise ratio threshold to screen frequency characteristics of the data; uses a Pytorch reconstruction network to realize mapping from one-dimensional voltage data to multi-dimensional magnetic particle concentration distribution; uses the system matrix as a forward model of magnetic particle imaging, generates voltage simulation data from the reconstructed magnetic particle concentration distribution, calculates a difference between the voltage simulation data and input voltage data as a loss function to update network parameters; adds a regularization term in the loss function, and adjusts training parameters and regularization parameters to obtain optimal reconstruction effect. The application uses a forward model constrained neural network to perform magnetic particle imaging reconstruction, and further improves the reconstruction effect by adding a total variation regularization term in the loss function of the network.

A magnetic particle imaging device comprises a detection coil (3) for detecting changes in the magnetism of magnetic particles (1), a compensating coil (4) which has a common central axis (CA) with the detection coil (3) and is connected to the detection coil (3) with opposite polarity, a first winding frame (21) for holding the detection coil (3), and a second winding frame (22) for holding the compensating coil (4). The distance between the detection coil (3) and the compensating coil (4) in one direction of the central axis (CA) is made variable by increasing or decreasing a contact section of the first winding frame (21) and the second winding frame (22).

A pair of first measurement coils is disposed so as to sandwich magnetic particles. A pair of second measurement coils is disposed so as to sandwich magnetic particles and the pair of first measurement coils. A pair of alternate-current magnetic field application coils is disposed so as to sandwich magnetic particles, the pair of first measurement coils, and the pair of second measurement coils. A measurement device outputs a signal representing a difference between a signal measured by the pair of first measurement coils and a signal measured by the pair of second measurement coils.

The application relates to the technical field of magnetic particle imaging, and more particularly to an iron oxide nanoparticle and application of the iron oxide nanoparticle in magnetic particle imaging. The nanoparticle is an octahedral superparamagnetic ferroferric oxide nanoparticle, the nanoparticle is synthesized by adding a surfactant and controlling a reaction rate through a high-temperature thermal decomposition method, the surfactant includes oleic acid and oleylamine, the octahedral superparamagnetic ferroferric oxide nanoparticle is coated with an amphiphilic polymer, the amphiphilic polymer includes polymaleic anhydride-1-octadecenoic acid and polystyrene maleic anhydride copolymer, and the outer layer of the amphiphilic polymer includes biological membranes such as macrophage membranes, red blood cell membranes, neutrophil membranes and tumor cell membranes according to biological application requirements. The surface of the octahedral magnetic particle is a crystal face, the crystal face has low spin disorder and low anisotropy, so that the octahedral magnetic particle has the advantages of low coercivity and high initial magnetic susceptibility, and thus becomes a high-sensitivity magnetic particle imaging tracer.

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.