162 results about "Magnetic particle imaging" patented technology

The invention belongs to the technical field of magnetic particle imaging, relates to a magnetic particle imaging reconstruction method based on a calibration magnetic field generation system matrix, and aims to solve the problems that a traditional magnetic particle imaging reconstruction method is poor in applicability in asymmetric bilateral structure magnetic particle imaging equipment (A-MPI) and cannot perform imaging in any region. The method comprises the following steps: performing grid division on an imaging area, calibrating magnetic field intensity, and obtaining magnetic field gradient distribution of each point; obtaining a theoretical system matrix according to a mathematical calculation mode; randomly moving the positions of the non-magnetic field points for scanning to obtain actually measured magnetic field gradient distribution and a system matrix, and constructing a data set; expanding the data set based on the simulation system; constructing a deep learning model, and inputting the extended data set and the measured data into the training deep learning model; and inputting a theoretical system matrix at any position, and obtaining an accurate system matrix by using the trained model. According to the invention, the system matrix at any position can be obtained under the A-MPI equipment, so that imaging at any position is realized.

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 magnetic particle imaging, particularly relates to a magnetic particle high-resolution reconstruction method based on fast feature fusion, and aims to solve the problems that an existing magnetic particle reconstruction method is slow in system matrix calibration, low in reconstructed magnetic particle image resolution, limited in signal-to-noise ratio and the like. The method comprises the following steps: collecting a system matrix generated by using a standard particle sample as a low-resolution system matrix; acquiring a voltage signal of the to-be-imaged phantom; inputting the low-resolution system matrix into the trained fast feature fusion Transform model to obtain a high-resolution system matrix; and based on the voltage signal, reconstructing the high-resolution system matrix to obtain a high-resolution MPI image. According to the method, the resolution of the MPI image is improved by carrying out rapid super-division on the system matrix, tedious and time-consuming calibration in system matrix reconstruction is avoided, in addition, resolution and signal-to-noise ratio improvement can be carried out on any system matrix, and a scanning mode related to the system matrix is not needed.

The invention belongs to the technical field of magnetic particle imaging, particularly relates to a magnetic particle imaging system and method based on a flexible receiving coil array, and aims to solve the problems that an existing rigid receiving coil is poor in biological surface adaptability and low in signal-to-noise ratio for micro geometric texture imaging. According to the structure, a receiving coil array adheres to the surface of an object to be measured, the receiving coil array and a compensation coil array are distributed on the two sides of a flexible substrate, the receiving coil array is used for receiving magnetic nanoparticle signals, and the partitioned small compensation coil array is used for conducting feed-through interference and electromagnetic interference compensation on a receiving coil; the reconstruction method comprises the following steps: sequentially carrying out Fourier transform on the collected receiving signals, extracting in-phase third harmonics and superposing to obtain processed signals, interpolating to construct a sinogram for Cartesian coordinate distribution, and reconstructing the three-dimensional particle concentration distribution of a measured object by a filtering back projection method. A flexible receiving coil array strategy is adopted, an adaptive reconstruction method is provided, and the imaging signal-to-noise ratio is improved.

The invention belongs to the technical field of magnetic nanoparticle imaging, particularly relates to an MPI magnetic particle imaging method and system for early detection of an AD patient, and aims to complete MPI time sequence imaging by using a diffusion model and solve the problem that the feature dimension of an input signal in the diffusion model is not matched with the resolution of an expected generated image. The method comprises the following steps: constructing a generative network model, and performing staged training; mPI time sequence one-dimensional signals are collected, and image reconstruction is carried out based on the generative network model to obtain MPI time sequence images; carrying out registration and dividing a brain region; and constructing a functional connection diagram and a functional connection matrix by using the RV coefficient, and drawing the brain network. According to the method, by constructing the Seq-VAE / Regression / Sig-LDM step-by-step network and performing staged training, free input of a signal sequence of a fixed feature dimension is realized, the image sequence reconstruction effect is improved, a default mode network is drawn based on the reconstructed image sequence, and accurate data is provided for subsequent application.

The invention discloses a multi-metal borate nano-particle as well as a preparation method and application thereof. The preparation method comprises the following steps: in the presence of small molecules with alkyl chains, performing high-temperature thermal decomposition on an organic metal compound or a metal salt compound precursor and organic borate in a solvent, and then centrifuging, modifying, performing ultrafiltration, dialyzing and purifying to obtain the multi-metal borate nanoparticles. The preparation method disclosed by the invention has the characteristics of mildness, high efficiency and strong controllability. The multi-metal borate nanoparticles prepared by the preparation method disclosed by the invention have the advantages of monodisperse size, relatively high magnetic property and good biocompatibility. Therefore, the prepared multi-metal borate nanoparticles not only have multi-modal imaging functions such as magnetic resonance imaging, near-infrared two-region imaging, nuclear medicine imaging and magnetic particle imaging, but also can be used for various treatment means such as magnetocaloric therapy and boron neutron capture therapy; potential advantages are realized in biomedical applications such as magnetic targeting tumor treatment and imaging contrast agents, and high practical values are realized.

The invention discloses a Brazilian splitting experiment device and method based on multiple heating modes, and belongs to the technical field of splitting experiments. Comprising a base, a Brazilian splitting clamp, a kettle body, a heating system, a heat transfer fluid injection hole, an axial pressure head, a temperature and pressure monitoring and heat transfer fluid outlet, a magnetic particle imaging system and a high-temperature early warning system, the temperature and pressure monitoring and heat-carrying fluid outlet is used for being connected with an external real-time observation system to conduct temperature and pressure monitoring and serves as an outlet of heat-carrying fluid at the same time. The magnetic particle imaging system is used for observing the distribution state of nano magnetic induction particles in the kettle body; the real-time high-temperature Brazilian splitting experiment can be carried out in multiple heating modes such as convection heating, conduction heating and supercritical fluid heating, the generation and expansion process of cracks in a sample can be monitored in real time, and the device is suitable for testing the strength and crack expansion of rocks under the thermal stress condition possibly encountered in actual engineering.

The invention belongs to the technical field of magnetic particle imaging, particularly relates to a stacked high-uniformity magnetic field free line magnetic particle imaging system and method, and aims to solve the problems that magnetic field free lines in an existing FFL-MPI are not uniform, imaging resolution is not uniform, and circumferential artifacts exist. The system comprises a laminated gradient coil unit composed of N groups of symmetrical coil pairs, each group comprising n layers of coils with increasing diameters, and a saddle-shaped driving scanning coil and a detection coil; through a reverse current mode of two adjacent layers of coils, the magnetic field amplitude is opposite to the current direction, the non-uniformity of the magnetic field is compensated, and a high-uniformity FFL gradient field is generated; the control system accurately collects and processes signals, the signals are fed back to the imaging unit after analog-to-digital conversion, amplification and filtering, and imaging is reconstructed through an imaging algorithm. According to the invention, the problems of non-uniform resolution and circumferential artifacts caused by non-uniform magnetic field are solved, and the imaging quality of FFL-MPI equipment is remarkably improved.

The invention belongs to the technical field of magnetic particle imaging, and relates to a magnetic particle imaging method based on mixed-frequency magnetic field excitation, which comprises the following steps: acquiring a dotted magnetic nanoparticle sample and a to-be-imaged object, respectively applying a mixed-frequency excitation magnetic field in an imaging mode to the dotted magnetic nanoparticle sample and the to-be-imaged object, acquiring a mixed frequency magnetic field excitation-based system matrix and a mixed frequency domain magnetization response frequency spectrum signal; and inputting the system matrix and the mixed frequency domain magnetization response frequency spectrum signal into a concentration spatial distribution inversion model to perform concentration spatial distribution inversion of the magnetic nanoparticles, obtaining the concentration spatial distribution of the magnetic nanoparticles in the object to be imaged, and performing magnetic particle concentration distribution imaging. According to the invention, real-time high-resolution magnetic particle imaging can be realized.

The invention discloses a magnetic particle imaging signal processing link and method based on adjustable external compensation, and the link is characterized in that a signal generator is respectively connected with the input ends of a first power amplifier and a second power amplifier through a first output end and a second output end, the output end of the first power amplifier is connected with the input end of a first capacitor, and the output end of the second power amplifier is connected with the input end of a second capacitor; the output end of the first capacitor is connected with the input end of the receiving excitation module, the output end of the second power amplifier is connected with the input end of the second capacitor, the output end of the second capacitor is connected with the input end of the compensation excitation module, and the output ends of the receiving excitation module and the compensation excitation module are connected with the input end of the low-noise amplifier. The output end of the low-noise amplifier is connected with the input end of the acquisition card, the output end of the acquisition card is connected with the input end of the central processing unit, and the output end of the central processing unit is connected with the input end of the signal generator. According to the invention, the sensitivity and the imaging quality of the MPI equipment are obviously improved.

A three-dimensional (3D) magnetic particle imaging (MPI) method and system without rotating a field-free line (FFL) are disclosed. In accordance with the method, an FFL is generated such that magnetic particles in a region far from the FFL enter a magnetic saturation state. Further, a non-uniform mixed-frequency excitation magnetic field parallel to the FFL is applied to generate intermodulation response signals. In addition, the intermodulation response signals are acquired, amplified and filtered. Moreover, the intermodulation response signals are transmitted to a digital signal processing unit and an image reconstruction unit, and an encoding matrix is constructed. Additionally, a one-dimensional (1D) concentration distribution of the magnetic particles is reconstructed based on the encoding matrix and an actually measured voltage signal. The FFL is driven for line-by-line scanning along a vertical plane of the FFL, thereby achieving 3D imaging.

The invention belongs to the technical field of magnetic particle imaging, particularly relates to a time sequence magnetic nanoparticle imaging device and method for detecting nerve response activity, and aims to solve the problems that the sensitivity of magnetic particle signal detection is not high, a large coil assembly is needed for achieving high magnetic field intensity, the calculation amount is large, and the calculation mode is complex. According to the device, a signal generator outputs a voltage signal, amplifies the voltage signal and then accesses a selection coil and a driving coil; the two selection coils are arranged in a Maxwell configuration and have the same axis; the driving coils are arranged at intervals of 90 degrees from top to bottom, from left to right and from front to back by taking the FFR as the center; the excitation coil, the receiving coil and the selection coil are coaxial; and the high-pass filter filters the signal received by the receiving coil and imports the signal into a computer through a signal acquisition card for time sequence fMPI image sequence reconstruction. According to the invention, the magnetic particle signal detection sensitivity is improved, the volume of the coil assembly is reduced, the calculation complexity and the calculation amount are simplified, and the magnetic particle imaging robustness is improved.

The invention discloses a rock permeability testing system in a high-temperature and high-pressure environment and a using method thereof, and belongs to the technical field of geothermal development or coal in-situ gasification mining. The test system is composed of a stress loading system, a test kettle assembly and a magnetic particle imaging system. When in use, the stress loading system and the test kettle assembly provide conditions such as high temperature, high pressure, seepage fluid and the like for a test piece; and detecting the spatial distribution state of the nano magnetic induction particles added in the seepage fluid through a magnetic particle imaging system to observe the pore and crack distribution characteristics in the test piece or detecting the nano magnetic induction particles added in the pollutant solution to observe the pollutant migration condition. The test system is scientific in design, simple in structure and easy to operate and maintain, can monitor pore fracture distribution and pollutant migration conditions in the test piece in real time under high-temperature and high-pressure conditions, provides accurate dynamic observation data, and provides important technical support for reservoir assessment and optimization in a complex environment.

The invention belongs to the field of magnetic particle imaging, particularly relates to a zero-inertia magnetism gathering ring magnetic-field-free line magnetic particle imaging system and method, and aims to solve the problems of low magnetic field gradient, high magnetic field control complexity and limited imaging space. The current of a gradient magnetic field coil group is generated by a magnetic field control and imaging module, is output by a signal acquisition and output module, and is amplified and provided by a gradient power amplifier module. The current of the axial excitation magnetic field coil is generated by the magnetic field control and imaging module, is output by the signal acquisition and output module and is amplified and provided by the excitation power amplifier module, and a signal received by the multi-axis detection coil is filtered and amplified by the signal processing unit and then is input to the imaging module by the magnetic field control and imaging module for algorithm reconstruction. According to the invention, the magnetic field gradient and the control precision are obviously improved, and the imaging space of the axial fault plane is realized.

The invention relates to the technical field of magnetic particle imaging, in particular to a non-magnetic field line three-dimensional magnetic particle imaging method and system based on weak gradient coding, and the method comprises the steps: driving a zero magnetic field line to carry out the spiral scanning of an imaging object; exciting a nonlinear response signal generated by magnetic particles of the imaging object; obtaining a two-dimensional image of magnetic particle concentration distribution in the imaging object; performing spatial position coding on the zero magnetic field line; obtaining target magnetic particle concentration distribution on the zero magnetic field line; and obtaining a three-dimensional image of the magnetic particle concentration distribution in the imaging object. According to the invention, the zero magnetic field line along the axial direction is constructed, and the Halbach permanent magnet array is driven to carry out visual field scanning of two-dimensional imaging. Two-dimensional imaging is carried out by adopting axial projection, then three-dimensional reconstruction is carried out under the guidance of the two-dimensional reconstruction image, and the three-dimensional reconstruction image is reconstructed by encoding the zero magnetic field line, that is, the three-dimensional image reconstruction can be completed only by scanning twice, and the imaging speed is higher compared with the traditional three-dimensional tomography.

The invention provides a magnetic particle imaging equipment system matrix calibration method, device and equipment. The method comprises the steps of performing sampling processing on a preset two-dimensional slice layer based on a cross down-sampling method to obtain original LR SM data; the preset two-dimensional slice layer is each two-dimensional slice layer in the three-dimensional FOV of the MPI equipment; performing frequency screening on the original LR SM data to obtain high signal-to-noise ratio LR SM data; converting each row of the high-signal-to-noise-ratio LR SM data into a three-dimensional structure to obtain a plurality of pieces of three-dimensional LR SM data; taking the L layer and the L + 1 layer of each three-dimensional LR SM data as first input data, and inputting the first input data into a pre-training system matrix calibration network to perform system matrix calibration processing on the L layer of the three-dimensional LR SM data to obtain calibrated HR SM data; the adjacent layers of the preset two-dimensional slice layer are subjected to dislocation sampling, so that more prior information of each slice layer can be obtained, and the system matrix calibration precision 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 provides a magnetic particle imaging image processing method and device, which can be applied to the technical field of image processing. The method comprises the following steps: performing noise enhancement processing on a magnetic particle imaging noise image by using a Gaussian noise network to obtain a target noise image; n cascaded down-sampling attention layers are utilized to perform multi-level feature extraction on the target noise image to obtain N image features, and the down-sampling attention layers are constructed based on L cascaded down-sampling attention excitation sub-layers; performing feature fusion on the Nth image feature by using a grayscale adaptive learning network layer to obtain an image grayscale enhancement feature, the grayscale adaptive learning network layer being obtained based on adaptive grayscale enhancement learning parameter adjustment; and processing the N image features and the image gray level enhancement features by using N cascaded up-sampling attention layers to obtain a magnetic particle imaging de-noised image, the up-sampling attention layers being constructed based on L cascaded up-sampling attention excitation sub-layers.

The invention belongs to the field of biomedical imaging, particularly relates to a multicolor magnetic particle imaging method and system based on magnetic field free line projection decoding, and aims to solve the problems of low imaging efficiency and quality caused by the absence of a relaxation-based multicolor imaging method by using a magnetic field free line in the prior art. The method comprises the following steps: respectively placing N kinds of magnetic nanoparticles in an imaging view center for scanning, and obtaining a time-frequency spectrum center spectral line by adopting time-frequency analysis; scanning an imaging object, acquiring a voltage response signal and performing time-frequency analysis to obtain a time-frequency spectrum; a linear equation set is constructed and solved, and all unknown quantities are obtained; discretely rotating the free line of the magnetic field by P angles, and obtaining the content distribution of N magnetic nanoparticles at each angle; and constructing a sinogram of the N magnetic nanoparticles, performing back projection reconstruction to obtain multicolor images, and superposing the multicolor images to obtain a reconstructed image. According to the invention, relaxation-based multicolor imaging is realized by using the free line of the magnetic field, and the imaging efficiency and quality are improved.

The invention provides an acid response magnetic particle imaging probe and a preparation method and application thereof.The preparation method comprises the steps that S1, a magnetic core, an iron precursor and long-chain alcohol diol are dispersed in a mixed solution of oleic acid, oleylamine, cyclohexane and octadecene, a reaction is conducted for 30-90 minutes under the inert atmosphere condition of 200-300 DEG C, a first non-polar solvent is used for washing, precipitation and centrifugation, and a first non-polar solvent is obtained; the oil-phase double-magnetic core-shell nanoparticles are obtained; s2, preparing water-phase aminated double-magnetic core-shell nanoparticles from the oil-phase double-magnetic core-shell nanoparticles and polymers with amino groups by adopting a film dispersion method or a nano coprecipitation method; s3, the aqueous-phase aminated double-magnetic core-shell nanoparticles and a compound with multiple aldehyde groups are subjected to an aldehyde-amine condensation reaction, a stable imine bond mediated nanometer assembly structure is formed, and the acid response magnetic particle imaging probe is obtained. The probe provided by the invention can respond to the change of the acid microenvironment, has high sensitivity, low background noise and a relatively strong imaging effect, and is suitable for dynamically monitoring diseases related to the acid microenvironment in real time.

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 field of magnetic particle imaging, particularly relates to a three-dimensional magnetic particle imaging enhancement method and system based on distillation structure contrast learning, and aims to solve the problems of anisotropic resolution and background noise interference caused by sparse scanning tracks in three-dimensional magnetic particle imaging. The method comprises the following steps: constructing a data set; building a two-dimensional isotropic teacher network model and a three-dimensional resolution improvement student network model; training a two-dimensional isotropic teacher network model and storing model parameters; the three-dimensional resolution improvement student network model obtains model parameters and then carries out training, an obtained three-dimensional training result is converted into two-dimensional training input data, and the two-dimensional training input data is input into the two-dimensional isotropic teacher network model to generate a supervision benchmark which is used for updating and optimizing the three-dimensional resolution improvement student network model; and after training, carrying out resolution improvement processing on the input three-dimensional magnetic particle imaging image. According to the method, the isotropic resolution of the three-dimensional magnetic particle image is improved, and background noise is effectively suppressed.

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 present invention belongs to the technical field of medical imaging detection, and particularly relates to a method for rapid calibration of a matrix of a magnetic particle imaging system, including: performing spatial discretization on an imaging region and setting magnetic particle imaging magnetic field configuration parameters; obtaining magnetic particle magnetization response spectrum information at different spatial positions of field-free points; obtaining magnetic particle magnetization response spectrum information at different magnetic particle spatial positions based on the principle of equivalent substitution; calculating and assembling to obtain a matrix of the magnetic particle imaging system. According to the symmetry of the magnetic particle imaging gradient magnetic field, the present invention uses the movement of the spatial position of the field-free point to replace the mechanical movement of the magnetic particle spatial position, realizes the rapid calibration of the matrix of the magnetic particle imaging system, and significantly shortens the calibration time.

The present invention belongs to the field of magnetic particle imaging, and specifically relates to a zero-inertia magnetic focusing ring magnetic particle imaging system and method without magnetic field lines, aiming to solve the problems of low magnetic field gradient, high complexity of magnetic field control, and limited imaging space. The present invention includes: the current of the gradient magnetic field coil group is generated by the magnetic field control and imaging module, output through the signal acquisition and output module, and amplified by the gradient power amplifier module. The current of the axial excitation magnetic field coil is generated by the magnetic field control and imaging module, output through the signal acquisition and output module, and amplified by the excitation power amplifier module. The signals received by the multi-axis detection coil are filtered and amplified by the signal processing unit, and then input to the imaging module by the magnetic field control and imaging module for algorithm reconstruction. The present invention not only significantly improves the magnetic field gradient and control accuracy, but also realizes the imaging space of the axial cross-section.

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.