Magnetic particle imaging method and system based on data rearrangement

Abstract

The invention belongs to the technical field of magnetic nanoparticle imaging, relates to a magnetic particle imaging method and system based on data rearrangement, and aims to solve the problem of information aliasing between adjacent pixels caused by a repeated scanning phenomenon in the prior art. The method comprises the steps of generating a first magnetic field and starting a second magnetic field; performing one-dimensional scanning on the first magnetic field and performing image reconstruction; acquiring a time sequence waveform of the second magnetic field and a time sequence voltage response signal of the magnetic nanoparticles; segmenting the time sequence waveform of the second magnetic field, extracting segments of each waveform segment, reconstructing the segments into a sine sequence, recording an index, rearranging the voltage response signal based on the index, and generating a one-dimensional reconstruction result; and constructing a two-dimensional image on the basis of data rearrangement of the one-dimensional image. According to the method, the fragments of each waveform segment are extracted for reconstruction, and the time sequence signals are rearranged and spliced, so that aliasing information is rearranged and analyzed, deviation and blurring phenomena in the reconstruction process are reduced, and the spatial resolution of the image is improved.

Description

Background Art

[0002] Magnetic Particle Imaging (MPI), as a highly potential non-invasive imaging technology, has received extensive attention in the fields of biomedical imaging and the like in recent years. By applying an external magnetic field, utilizing the non-linear magnetization response of magnetic nanoparticles, capturing these signals to obtain their in-vivo concentration distribution, and converting it into an image of the particle distribution with the aid of imaging algorithms, the visualization of the imaging object can be achieved, which has important medical application value. The external magnetic field consists of a selection magnetic field and an excitation magnetic field. Among them, the selection magnetic field is characterized by a gradient magnetic field with a punctiform low magnetic field region (Field Free Point, FFP) or a gradient magnetic field with a linear low magnetic field region (FieldFree Line, FFL). The magnetic nanoparticles in the low magnetic field region can be magnetized, while those in the high magnetic field region are magnetically saturated and cannot be magnetized. The excitation magnetic field is characterized by a uniform alternating magnetic field, which is used to drive the scanning of the punctiform or linear low magnetic field region to achieve spatial encoding of the imaging field of view.

[0003] However, during the imaging process, when the movement trajectories of the FFP or FFL cover the entire imaging field of view, there is inevitably a phenomenon of repeated scanning; this leads to information aliasing between adjacent pixels, thus affecting the accuracy of signal analysis and interfering with the image reconstruction process, becoming a potential factor reducing the image spatial resolution. How to effectively analyze and rearrange the aliased information generated by repeated scanning and further improve the imaging quality has become a key technical problem to be solved urgently. Summary of the Invention

[0004] In order to solve the above problems in the prior art, that is, the problem of information aliasing between adjacent pixels caused by the repeated scanning phenomenon, the first aspect of the present invention proposes a magnetic particle imaging method based on data rearrangement to analyze and rearrange the aliased information, thereby improving the imaging quality. The method includes the following steps: S100. Generate a first magnetic field, set a second magnetic field as the excitation magnetic field and start the second magnetic field; the first magnetic field is a field free point or a field free line; S200. Drive the first magnetic field for one-dimensional scanning and perform image reconstruction: S201. Collect the time series waveform of the second magnetic field and the time series voltage response signal of the magnetic nanoparticles, and uniformly segment the time series waveform and the time series voltage response signal on the amplitude axis to obtain waveform segments and voltage response signal segments; the waveform segments and the voltage response signal segments correspond one by one; S202. Extract each segmented waveform segment and reconstruct it to obtain a reconstructed sine sequence; assign a unique index to each sine sequence and record the index; S203. Rearrange the corresponding voltage response signal segments based on the index to obtain a time-sequence rearranged response signal; S204. Extract the maximum value of each segmented time-sequence rearranged response signal and splice them in the segmented order to obtain a one-dimensional reconstruction result; S300. Based on the one-dimensional reconstruction result, construct a two-dimensional image using a set scanning method; the set scanning method includes row-by-row scanning and discrete rotation at multiple angles.

[0005] In some preferred embodiments, the second magnetic field is composed of a superposition of a triangular waveform and a sine waveform, and the magnetic field directions generated by the triangular waveform and the sine waveform are the same.

[0006] In some preferred embodiments, the amplitude of the sine waveform is: ; The amplitude of the triangular waveform is: ; where L is the side length of the imaging field of view, the imaging field of view is square, and the image size is N×N; G is the first magnetic field gradient.

[0007] In some preferred embodiments, the second magnetic field time-sequence waveform is uniformly segmented on the amplitude axis, the length of each segment is L / N, and the segmentation result is discrete waveform segments.

[0008] In some preferred embodiments, the method for extracting each waveform segment and reconstructing it into a sine sequence is as follows: Determine the period length of the sine waveform, and define the length of one period as W; For each waveform segment to be processed, divide it according to the length W to obtain multiple segments; Augment and splice the obtained multiple segments in the column direction to reconstruct them into a sine sequence.

[0009] In some preferred embodiments, the splicing method is signal numerical addition.

[0010] In some preferred embodiments, the first magnetic field is a magnetic field free point, and the method for constructing a two-dimensional image is as follows: Adopt a Cartesian trajectory to arrange the one-dimensional reconstruction result row by row or column by column to construct a two-dimensional image.

[0011] In some preferred embodiments, the first magnetic field is a magnetic field free line, and the method for constructing a two-dimensional image is as follows: Adopt a discrete rotation trajectory for multi-angle scanning; use the one-dimensional reconstruction results at multiple angles to construct a sinogram, and then construct a two-dimensional image through filtered backprojection.

[0012] In some preferred embodiments, the filtered backprojection uses a Cosine filter or an R-L filter.

[0013] In a second aspect of the present invention, a magnetic particle imaging system based on data rearrangement is proposed. The system includes: A power supply module configured to provide power supply to the coil magnet and other modules in the entire imaging system; A control module configured to generate control signals; A magnetic field generation module configured to generate a first magnetic field according to the control signal, set a second magnetic field as an excitation magnetic field and start the second magnetic field, and then drive the first magnetic field for one-dimensional scanning; A signal processing and acquisition module configured to collect the timing waveform of the second magnetic field and the timing voltage response signal of the magnetic nanoparticles and perform preprocessing, and send the preprocessed timing waveform and the timing voltage response signal to the image reconstruction and visualization module; A memory storage module configured to store the collected timing waveform of the second magnetic field, the timing voltage response signal of the magnetic nanoparticles, and the constructed two-dimensional image; An image reconstruction and visualization module configured to perform image reconstruction according to the received timing waveform and the timing voltage response signal: Uniformly segment the timing waveform and the timing voltage response signal on the amplitude axis to obtain waveform segments and voltage response signal segments; extract and reconstruct each segmented waveform segment to obtain a reconstructed sine sequence; assign a unique index to each sine sequence and record the index; Based on the index, rearrange the corresponding voltage response signal segments to obtain a timing rearranged response signal; extract the maximum value of each segmented timing rearranged response signal and splice them in the segmented order to obtain a one-dimensional reconstruction result; construct a two-dimensional image based on the one-dimensional reconstruction result by line-by-line scanning or discrete rotation multi-angle scanning.

[0014] Advantages of the present invention: By segmenting the timing waveform of the second magnetic field, extracting and reconstructing the segments of each waveform segment and recording the index at the same time, rearranging and splicing the timing signals based on the recorded index to generate a one-dimensional reconstruction result, and rearranging and analyzing the aliased information, the present invention improves the imaging quality and the image spatial resolution; Index-based rearrangement ensures the correspondence between the signal and the timing waveform of the excitation magnetic field. Through waveform segmentation and grouping, signal rearrangement, and amplitude extraction, the accuracy and efficiency of imaging are improved, information aliased due to repeated scanning is accurately separated, and errors and interferences caused by information aliasing are effectively eliminated in the optimal logical order required for imaging, providing a reliable basis for subsequent image reconstruction. During two-dimensional image reconstruction, based on the rearranged data, the true distribution of magnetic nanoparticles in the body can be restored more accurately, reducing deviations and blurring phenomena during the reconstruction process. Description of the Drawings

[0015] Other features, objects, and advantages of the present application will become more apparent by reading the detailed description of the non-limiting embodiments with reference to the following drawings: Figure 1 is a flowchart of the magnetic particle imaging method based on data rearrangement in an embodiment of the present invention; Figure 2 is a schematic diagram of the timing waveform of the second magnetic field in an embodiment of the present invention; Figure 3 is a schematic diagram of one of the waveform segments after segmenting the second magnetic field by amplitude in an embodiment of the present invention; Figure 4 is a schematic diagram of constructing a sine sequence using waveform segments in an embodiment of the present invention; among them, the upper figure shows equidistant grouping of waveform segments in the time series, and the lower figure shows augmenting and splicing the grouped segments in the upper figure by columns to form a sine sequence; Figure 5 is a comparison schematic diagram of the magnetic nanoparticle response signal before rearrangement and after rearrangement in an embodiment of the present invention. Among them, a unit magnetic nanoparticle sample is placed at the center of the field of view in one-dimensional scanning. The left side shows the response signal before data rearrangement, and the right side shows the response signal after data rearrangement; Figure 6 is a schematic diagram of the scanning process of the two-dimensional imaging field of view when the first magnetic field is at the magnetic field free point in an embodiment of the present invention; Figure 7 is a schematic diagram of one-dimensional scanning and two-dimensional multi-angle scanning of the magnetic field free line in an embodiment of the present invention. Detailed Embodiments

[0016] The present application will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related invention and do not limit the invention. Additionally, it should be noted that for the sake of description, only parts related to the relevant invention are shown in the drawings.

[0017] 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.

[0018] The present invention performs secondary grouping on segmented waveforms, augments and splices them column by column to splice the segments into a sine sequence, rearranges the timing signals based on the indexes of the sine sequence, and then constructs a two-dimensional image on the basis of data rearrangement in a one-dimensional image, parses and rearranges the aliased information, thereby improving the imaging quality.

[0019] To more clearly illustrate the magnetic particle imaging method based on data rearrangement of the present invention, the following combines Figure 1 to elaborate on each step in the embodiments of the present invention.

[0020] A magnetic particle imaging method based on data rearrangement according to a first embodiment of the present invention, the method comprising steps S100 - S300: S100, generate a first magnetic field, set a second magnetic field as an excitation magnetic field and start the second magnetic field; the first magnetic field is a magnetic field free point or a magnetic field free line.

[0021] Preferably, the second magnetic field is composed of a superposition of a triangular waveform and a sine waveform.

[0022] Preferably, the amplitude of the sine waveform is: ; The amplitude of the triangular waveform is: ; wherein, L is the side length of the imaging field of view, the imaging field of view is square, and the image size is N×N; G is the first magnetic field gradient.

[0023] Preferably, the magnetic fields generated by the triangular waveform and the sine waveform have the same direction.

[0024] S200, drive the first magnetic field to perform one-dimensional scanning and perform image reconstruction; the method of the image reconstruction is: S201, collect the timing waveform of the second magnetic field and the timing voltage response signal of the magnetic nanoparticles, and uniformly segment the timing waveform and the timing voltage response signal on the amplitude axis to obtain waveform segments and voltage response signal segments; the waveform segments and the voltage response signal segments correspond one by one; Further, uniformly segment the second magnetic field timing waveform on the amplitude axis, and the segmentation length is L / N, and the segmentation result is discrete waveform segments; S202, extract and reconstruct each segmented waveform segment to obtain a reconstructed sine sequence; assign a unique index to each sine sequence and record the index; S203, rearrange the corresponding voltage response signal segments based on the index to obtain a timing rearranged response signal; S204. Extract the maximum value of the time - series rearranged response signals described in each segment, and splice them in the segment order to form a one - dimensional reconstruction result.

[0025] Preferably, extract each waveform segment and reconstruct it into a sine sequence. The method is as follows: Determine the period length of the sine waveform, and define the length of one period as W; For each waveform segment to be processed, divide it according to the length W to obtain multiple segments; Augment and splice the obtained multiple segments along the column direction to reconstruct them into a sine sequence.

[0026] S300. Based on the one - dimensional reconstruction result, construct a two - dimensional image by line - by - line scanning or discrete rotational multi - angle scanning.

[0027] In the above - mentioned embodiments, although each step is described in the above - mentioned order, those skilled in the art can understand that in order to achieve the effect of this embodiment, different steps do not have to be executed in such an order. They can be executed simultaneously (in parallel) or in a reversed order, and these simple changes are all within the protection scope of the present invention.

[0028] A magnetic particle imaging method based on data rearrangement according to the second embodiment of the present invention. The first magnetic field uses a magnetic - field free point, and the gradient is set to 1 T / m. The imaging field of view is set to 40 mm×40 mm. The second magnetic field is used as the excitation magnetic field, and its waveform is as shown in the appendix Figure 2 It is composed of a triangular waveform superimposed on a sine waveform. The horizontal axis is the time axis representing the time series of the second - magnetic - field waveform, and the vertical axis is the amplitude axis representing the field - strength change of the second magnetic field. Among them, the amplitude of the triangular waveform is set to 40 mT, the frequency is set to 1 Hz, and only the process of the half - cycle from the negative peak to the positive peak is utilized; the amplitude of the sine waveform is set to 4 mT, and the frequency is set to 3000 Hz.

[0029] After placing the particle to be measured into the imaging field of view, start the excitation magnetic field; in the excitation magnetic field, the triangular waveform drives the magnetic - field free point to slowly and uniformly move from the left - most side to the right - most side of the imaging field of view, while the superimposed sine wave drives the magnetic - field free point to perform high - frequency oscillation to excite the nano - particles to generate a non - linear response signal, and the time - series voltage signal is acquired through a sensor.

[0030] In this embodiment, the particle to be measured is set as a point - like particle phantom, placed at the center of the imaging field of view, and one - dimensional scanning is performed. The time - series voltage response signal of the magnetic nanoparticles obtained by scanning is as shown in the left figure of the appendix Figure 5 It has a relatively wide envelope. Acquire the time - series waveform of the excitation magnetic field and the time - series voltage response signal of the magnetic nanoparticles; the acquired time - series waveform of the excitation magnetic field is as shown in the appendix Figure 2As shown, the timing waveform is segmented on the amplitude axis, and the segmentation length is the interval of 12 excitation periods. A segment of the waveform fragment extracted is as shown in the appendix Figure 3 As shown, the horizontal axis is the time axis representing the time series of the waveform fragment, and the vertical axis is the amplitude axis representing the amplitude of the waveform fragment; among them, two time windows are enlarged. The lower time window is the maximum peak fragment for rearranging and constructing the sine sequence, and the upper time window is the intermediate fragment near the maximum peak for rearranging and constructing the sine sequence.

[0031] Reconstruct each of the extracted waveform fragments, and the reconstruction process is as shown in the appendix Figure 4 As shown. According to the length of 12 excitation periods, the waveform fragments are divided into 8 groups. In the upper figure of the appendix Figure 4 is the waveform fragment of the second magnetic field and is equally divided into 8 groups at equal intervals in the time series. The lower figure is to augment and splice the 8 groups of fragments in the upper figure by columns to form a sine sequence, and a new sine sequence is constructed while recording the corresponding indexes after rearrangement.

[0032] According to the indexes obtained after rearranging the excitation magnetic field, rearrange the timing voltage signal to obtain a rearranged signal, as shown in the appendix Figure 5 As shown in the right figure: In the one-dimensional scan, a unit magnetic nanoparticle sample is placed at the center of the field of view. On the left is the response signal before data rearrangement, and on the right is the response signal after data rearrangement. For the rearranged signal, take the maximum value of each segment as the signal amplitude and splice them in sequence to obtain the one-dimensional reconstruction result. After completing the scan and reconstruction of one row, move the object to be measured forward by one pixel unit and perform the scan and reconstruction of the second row. According to this mode, complete the scan and reconstruction of all rows in the two-dimensional field of view and splice all rows to construct a two-dimensional image. The two-dimensional scan trajectory is as shown in the appendix Figure 6 As shown.

[0033] Preferably, in this embodiment, the splicing method is signal numerical addition.

[0034] A magnetic particle imaging method based on data rearrangement according to the third embodiment of the present invention. The first magnetic field uses a magnetic field free line, and the magnetic field parameters of the first magnetic field and the second magnetic field are set the same as those in Embodiment 2. Different from the magnetic field free point in the one-dimensional encoding process, after the magnetic field free line completes the same scan and reconstruction process, a projection at a certain angle is obtained. The process of the magnetic field free line performing one-dimensional scan is as shown in the appendix Figure 7 As shown in the left figure. After completing the one-dimensional scan and projection, a discrete rotation trajectory is adopted, as shown in the appendix Figure 7 As shown in the right figure.

[0035] Among them, the discrete rotation angles are recorded as the angle vector, the initial angle is recorded as 0, and the subsequent rotation angles are recorded in the angle vector; after the multi-angle scanning process is completed, a sinogram is constructed using the results of multi-angle scanning and reconstruction; the sinogram is filtered and back-projected, and a two-dimensional reconstructed image is obtained through back-projection.

[0036] Optionally, in this embodiment, the back-projection angle uses the recorded angle vector, the filter uses a Cosine filter or an R-L filter, and the interpolation parameter algorithm for back-projection uses spline interpolation.

[0037] In a fourth aspect of the present invention, a magnetic particle imaging system based on data rearrangement is proposed. The system includes: A power supply module configured to provide power supply to the coil magnet and other modules in the entire imaging system; A control module configured to generate control signals; A magnetic field generation module configured to generate a first magnetic field according to the control signal, set a second magnetic field as the excitation magnetic field and start the second magnetic field, and then drive the first magnetic field for one-dimensional scanning; A signal processing and acquisition module configured to acquire the timing waveform of the second magnetic field and the timing voltage response signal of the magnetic nanoparticles and perform preprocessing, and send the preprocessed timing waveform and the timing voltage response signal to the image reconstruction and visualization module; A memory storage module configured to store the acquired timing waveform of the second magnetic field, the timing voltage response signal of the magnetic nanoparticles, and the constructed two-dimensional image; An image reconstruction and visualization module configured to perform image reconstruction according to the received timing waveform and the timing voltage response signal: Uniformly segment the timing waveform and the timing voltage response signal on the amplitude axis to obtain waveform segments and voltage response signal segments; extract and reconstruct each segmented waveform segment to obtain a reconstructed sine sequence; assign a unique index to each sine sequence and record the index; Rearrange the corresponding voltage response signal segments based on the index to obtain a timing rearranged response signal; extract the maximum value of each segmented timing rearranged response signal and splice them in the segmented order to obtain a one-dimensional reconstruction result; construct a two-dimensional image based on the one-dimensional reconstruction result using line-by-line scanning or discrete rotation multi-angle scanning.

[0038] It should be noted that the magnetic particle imaging system based on data rearrangement provided in the above embodiments is only illustrated by the division of the above functional modules. In actual applications, the above functions can be allocated to different functional modules according to needs, 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 embodiments can be merged into one module, or further split into multiple sub-modules to complete all or part of the functions described above. The names of the modules and steps involved in the embodiments of the present invention are only for distinguishing each module or step, and are not regarded as an improper limitation of the present invention.

[0039] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process and related descriptions of the system described above can refer to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0040] An electronic device according to a fifth embodiment of the present invention includes: At least one processor; and A memory communicatively connected to at least one of the processors; wherein, The memory stores instructions executable by the processor, and the instructions are used to be executed by the processor to implement the above-mentioned magnetic particle imaging method based on data rearrangement.

[0041] A computer-readable storage medium according to a sixth embodiment of the present invention stores computer instructions, and the computer instructions are used to be executed by the computer to implement the above-mentioned magnetic particle imaging method based on data rearrangement.

[0042] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process and related descriptions of the above-described electronic device and computer-readable storage medium can refer to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0043] 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), internal 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 technical field. To clearly illustrate the interchangeability of electronic hardware and software, the composition and steps of each example have been generally described according to 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.

[0044] Computer program code for performing the operations of the present application can be written in one or more programming languages or combinations thereof. The above programming languages include object-oriented programming languages - such as Java, Smalltalk, C++, and also include conventional procedural programming languages - such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, executed as an independent software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer can be connected to the user's computer through any type of network - including a local area network (LAN) or a wide area network (WAN) - or, alternatively, can be connected to an external computer (for example, by using an Internet service provider to connect through the Internet).

[0045] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architectures, functions, and operations of systems, methods, and computer program products according to various embodiments of the present application. In this regard, each block in the flowchart or block diagram may represent a module, a program segment, or a part of code that contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than marked in the accompanying drawings. For example, two consecutive blocks shown may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, and the combination of blocks in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system for performing the specified functions or operations, or can be implemented by a combination of dedicated hardware and computer instructions.

[0046] The terms "first", "second", etc. are used to distinguish similar objects and are not used to describe or indicate a specific order or sequence.

[0047] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that comprises a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to those process, method, article, or apparatus / device.

[0048] 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 fall within the protection scope of the present invention.

Claims

1. A magnetic particle imaging method based on data rearrangement, characterized in that The method includes the following steps: S100. Generate a first magnetic field, set a second magnetic field as the excitation magnetic field and start the second magnetic field; the first magnetic field is a magnetic field free point or a magnetic field free line; S200. Drive the first magnetic field to perform one-dimensional scanning and perform image reconstruction: S201. Collect the time series waveform of the second magnetic field and the time series voltage response signal of the magnetic nanoparticles, and uniformly segment the time series waveform and the time series voltage response signal on the amplitude axis to obtain waveform segments and voltage response signal segments; the waveform segments and the voltage response signal segments correspond one by one; S202. Extract and reconstruct each segmented waveform segment to obtain a reconstructed sine sequence; assign a unique index to each sine sequence and record the index; S203. Rearrange the corresponding voltage response signal segments based on the index to obtain a time series rearranged response signal; S204. Extract the maximum value of each segmented time series rearranged response signal and splice them in the segmented order to obtain a one-dimensional reconstruction result; S300. Based on the one-dimensional reconstruction result, construct a two-dimensional image by using a set scanning method; the set scanning method includes line-by-line scanning and discrete rotation at multiple angles.

2. The magnetic particle imaging method based on data rearrangement according to claim 1, characterized in that, The second magnetic field is composed of the superposition of a triangular waveform and a sine waveform, and the magnetic field directions generated by the triangular waveform and the sine waveform are the same.

3. The magnetic particle imaging method based on data rearrangement according to claim 2, wherein, The amplitude of the sine waveform is as follows: ； The amplitude of the triangular waveform is: ； Wherein, L is the side length of the imaging field of view, the imaging field of view is square, and the image size is N×N; G is the first magnetic field gradient.

4. A magnetic particle imaging method based on data rearrangement according to claim 3, characterized in that, The time series waveform of the second magnetic field is uniformly segmented on the amplitude axis, and the length of each segment is L / N, and the segmentation result is discrete waveform segments.

5. A magnetic particle imaging method based on data rearrangement according to claim 4, characterized in that, The method for extracting each waveform segment and reconstructing it into a sine sequence is as follows: Determine the period length of the sine waveform, and define the length of one period as W; For each waveform segment to be processed, divide it according to the length W to obtain multiple segments; Augment and splice the obtained multiple segments in the column direction to reconstruct them into a sine sequence.

6. A magnetic particle imaging method based on data rearrangement according to claim 5, characterized in that, The splicing method is signal numerical addition.

7. A magnetic particle imaging method based on data rearrangement according to claim 1, characterized in that, When the first magnetic field is a magnetic field free point, the method for constructing a two-dimensional image is as follows: Adopt a Cartesian trajectory to arrange the one-dimensional reconstruction result row by row or column by column to construct a two-dimensional image.

8. A magnetic particle imaging method based on data rearrangement according to claim 1, characterized in that, When the first magnetic field is a magnetic field free line, the method for constructing a two-dimensional image is as follows: Adopt a discrete rotation trajectory to perform multi-angle scanning; use the one-dimensional reconstruction results at multiple angles to construct a sinogram, and then construct a two-dimensional image through filtered backprojection.

9. A magnetic particle imaging method based on data rearrangement according to claim 8, characterized in that, The filtered backprojection uses a Cosine filter or an R-L filter.

10. A magnetic particle imaging system based on data rearrangement, which is characterized by the magnetic particle imaging method based on data rearrangement according to any one of claims 1-9. The system includes: A power supply module configured to supply power to the coil magnet and other modules in the entire imaging system; A control module configured to generate control signals; A magnetic field generation module configured to generate a first magnetic field according to the control signal, set a second magnetic field as the excitation magnetic field and start the second magnetic field, and then drive the first magnetic field to perform one-dimensional scanning; A signal processing and acquisition module configured to collect the time series waveform of the second magnetic field and the time series voltage response signal of the magnetic nanoparticles and perform preprocessing, and send the preprocessed time series waveform and the time series voltage response signal to the image reconstruction and visualization module; A memory storage module, configured to store the collected second magnetic field timing waveform, the timing voltage response signal of the magnetic nanoparticles, and the constructed two-dimensional image; An image reconstruction and visualization module, configured to perform image reconstruction according to the received timing waveform and the timing voltage response signal: Uniformly segment the timing waveform and the timing voltage response signal on the amplitude axis to obtain waveform segments and voltage response signal segments; extract and reconstruct each segmented waveform segment to obtain a reconstructed sine sequence; assign a unique index to each sine sequence and record the index; Rearrange the corresponding voltage response signal segments based on the index to obtain a timing rearranged response signal; extract the maximum value of each segmented timing rearranged response signal and splice them in the segment order to obtain a one-dimensional reconstruction result; construct a two-dimensional image based on the one-dimensional reconstruction result by line-by-line scanning or discrete rotation multi-angle scanning.

Images