Double-color magnetic nanoparticle imaging method based on single harmonic system matrix

Abstract

The invention relates to a double-color magnetic nanoparticle imaging method based on a single-harmonic system matrix, which comprises the following steps: respectively moving two different types of magnetic nanoparticle samples to a central zero magnetic field point, applying a scanning magnetic field to enable the zero magnetic field point to scan the whole imaging field of view, applying an excitation magnetic field to magnetize magnetic nanoparticles, and applying an excitation magnetic field to magnetize the magnetic nanoparticles; acquiring magnetization frequency spectrum signals of the two magnetic nanoparticle samples; the method comprises the following steps: constructing single harmonic system matrixes A1 and A2 based on single harmonic of magnetization spectrum signals of two kinds of magnetic nanoparticle samples; measuring a to-be-measured object formed by the two kinds of magnetic nanoparticles to obtain a measurement magnetization signal U; transversely splicing the single harmonic system matrixes A1 and A2 of the two different types of magnetic nanoparticles to obtain a new single harmonic system matrix A; the concentration distributions c1 and c2 of two different types of magnetic nanoparticles are obtained by combining a new single-harmonic system matrix A with a measurement magnetization signal U, and the concentration distributions of the two different types of magnetic nanoparticles are respectively sent into different color channels to be displayed in different colors. The method has important significance in promoting the application of the magnetic nanoparticle imaging technology in clinical medicine.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic nanoparticle imaging, in particular to a dual-color magnetic nanoparticle imaging method based on a single harmonic system matrix. Background Art

[0002] Magnetic nanoparticle imaging is a new molecular imaging technology based on tracers. This technology detects the nonlinear magnetization response signal of magnetic nanoparticles to invert the spatial distribution of multiple parameters such as magnetic particle concentration, medium ambient temperature and viscosity, thereby achieving rapid and accurate imaging of the test area. This technology was proposed by German scientists in the early 21st century and has achieved rapid development in the past two decades. Compared with existing medical imaging technologies such as computed tomography, magnetic resonance imaging, optical imaging and radionuclide imaging, magnetic particle imaging technology has the characteristics of high sensitivity, high temporal and spatial resolution, no tissue depth limitation and no radioactivity. It is suitable for real-time monitoring of the fate of specific markers in vivo and has great application potential in medical imaging fields such as cell tracking, tumor detection, blood pool angiography and precision magnetic hyperthermia.

[0003] Two-color magnetic particle imaging involves scanning the detection area in a single pass to simultaneously obtain the concentration distribution of two different types of magnetic nanoparticles, representing each in different color channels, thereby achieving two-color quantitative visualization of the two different magnetic nanoparticles in the same color fusion image. The combination of magnetic nanoparticles with different characteristics and specific biomolecules is expected to achieve quantitative detection of multiple molecular markers in vivo, providing new insights into biomedical imaging. However, due to the doubling of the number of unknowns to be solved, crosstalk exists between the magnetic particle concentration signals of different color channels, resulting in low quantitative accuracy in two-color magnetic particle imaging.

[0004] Therefore, the present invention urgently needs a dual-color magnetic particle imaging method that can achieve the decoupling of the spatial distribution of two different magnetic nanoparticle concentrations, reduce the signal crosstalk between different particle channels, and improve the accuracy of solving the magnetic particle concentration distribution, so as to promote the application of magnetic nanoparticle imaging technology in clinical medicine. Summary of the Invention

[0005] To address the problems of the prior art described above, the present invention aims to provide a dual-color magnetic nanoparticle imaging method based on a single harmonic system matrix. By scanning the zero magnetic field point to obtain the magnetization response spectrum of the magnetic nanoparticles at different positions relative to the zero magnetic field point, and extracting the single harmonic signal of the magnetization response spectrum to construct a system matrix, the present invention maximizes the constraints on solving the concentration of the two magnetic nanoparticles, reduces the crosstalk between the concentration signals of different types of magnetic nanoparticles, and effectively improves the quantitative accuracy of dual-color magnetic nanoparticle imaging, which is of great significance for promoting the application of magnetic nanoparticle imaging technology in clinical medicine.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A dual-color magnetic nanoparticle imaging method based on a single harmonic system matrix, comprising:

[0008] Based on two different types of magnetic nanoparticles, the two different types of magnetic nanoparticle samples are respectively moved to the central zero magnetic field point, a scanning magnetic field is applied to make the zero magnetic field point scan the entire imaging field of view, and an excitation magnetic field is applied to magnetize the magnetic nanoparticles, thereby obtaining magnetization spectrum signals of the two magnetic nanoparticle samples; wherein the magnetization spectrum signals are generated by different types of magnetic nanoparticles at different positions relative to the zero magnetic field point; based on the single harmonics of the magnetization spectrum signals of the magnetic nanoparticle samples, single harmonic system matrices A1 and A2 are constructed;

[0009] Measuring the object to be measured composed of two types of magnetic nanoparticles to obtain a measured magnetization signal U;

[0010] The system matrices A1 and A2 of two different types of magnetic nanoparticles are horizontally spliced ​​to obtain a new single harmonic system matrix A;

[0011] The new single harmonic system matrix A is combined with the measured magnetization signal U to obtain the concentration distributions c1 and c2 of two different types of magnetic nanoparticles. The concentration distributions of the two magnetic particles are respectively sent to different color channels and displayed in different colors.

[0012] Optionally, obtaining the new single harmonic system matrix A includes:

[0013] A=[A1A2]

[0014] Among them, A1 and A2 are the single harmonic system matrices of the first magnetic nanoparticle sample and the second magnetic nanoparticle sample respectively.

[0015] Optionally, obtaining the concentration distributions of the two different types of magnetic nanoparticles includes:

[0016] According to the new single harmonic system matrix A and the measured magnetization signal U, a solution model for the magnetic nanoparticle concentration distribution c1 and c2 is constructed;

[0017] The two magnetic nanoparticle concentration distribution models are iteratively reconstructed to solve the spatial distribution of the concentrations of two different types of magnetic nanoparticles.

[0018] Optionally, constructing the magnetic nanoparticle concentration distribution model includes:

[0019] Ac=U

[0020] Where A is the new single harmonic system matrix, U is the measured magnetization signal, c is the concentration distribution of magnetic nanoparticles, and

[0021]

[0022] Optionally, solving the spatial distribution of concentrations of two different types of magnetic nanoparticles includes:

[0023] c k+1 =c k -(A T A+λI) -1 A T (A T c k -U)

[0024] Where k is the number of iterations, λ is the regularization factor, and I is the identity matrix.

[0025] The beneficial effects of the present invention are:

[0026] The present invention obtains the magnetization response spectrum of magnetic nanoparticles at different positions relative to the zero magnetic field point through zero magnetic field point scanning, and extracts the single harmonic signal of the magnetization response spectrum to construct a system matrix, thereby maximizing the constraints on solving the concentration of the two magnetic nanoparticles. When low-order harmonics are used for forward model construction, measurement data with a relatively high signal-to-noise ratio can be obtained, thereby effectively reducing the crosstalk of concentration signals between different magnetic nanoparticles, improving the accuracy and stability of concentration value solution, and effectively improving the quantitative accuracy of dual-color magnetic nanoparticle imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 This is a flow chart of a dual-color magnetic nanoparticle imaging method based on a single harmonic system matrix according to an embodiment of the present invention;

[0029] Figure 2 This is a flow chart of the Newton-Raphson iterative reconstruction algorithm according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the present invention, in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] like Figure 1 As shown, this embodiment discloses a dual-color magnetic nanoparticle imaging method based on a single harmonic system matrix, comprising: based on two different types of magnetic nanoparticles, moving two different types of magnetic nanoparticle samples to a central zero magnetic field point, applying a scanning magnetic field so that the zero magnetic field point scans the entire imaging field of view, applying an excitation magnetic field to magnetize the magnetic nanoparticles, and obtaining magnetization spectrum signals of the two magnetic nanoparticle samples; wherein the magnetization spectrum signals are generated by different types of magnetic nanoparticles at different positions relative to the zero magnetic field point; constructing single harmonic system matrices A1 and A2 based on a single harmonic of the magnetization spectrum signals of the magnetic nanoparticle samples; measuring an object to be measured composed of the two magnetic nanoparticles to obtain a measured magnetization signal U; horizontally splicing the system matrices A1 and A2 of the two different types of magnetic nanoparticles to obtain a new single harmonic system matrix A; obtaining concentration distributions c1 and c2 of the two different types of magnetic nanoparticles by combining the new single harmonic system matrix A with the measured magnetization signal U, and sending the concentration distributions of the two magnetic particles into different color channels for display in different colors.

[0033] Specifically, this embodiment discloses a dual-color magnetic nanoparticle imaging method based on a single harmonic system matrix, comprising:

[0034] Step S10: Using a magnetic nanoparticle imaging system, unit volume samples of two different types of magnetic nanoparticles are moved to the central zero magnetic field point, an excitation magnetic field is applied to the imaging field of view to magnetize the samples, and a scanning magnetic field is applied to move the zero magnetic field point for scanning, thereby obtaining magnetization spectrum signals of the two particles at different positions relative to the zero magnetic field point, and extracting single harmonics of the magnetization spectrum signals to construct single harmonic system matrices A1 and A2 of the two particles;

[0035] In step S20 , the object to be measured is placed in the imaging field of view, and an excitation magnetic field and a scanning magnetic field are also applied to collect a measurement magnetization signal U generated by the object to be measured.

[0036] Step S30, horizontally splicing the single harmonic system matrices A1 and A2 of the two magnetic nanoparticles to obtain a new single harmonic system matrix A;

[0037] A=[A1A2]

[0038] Step S40 : Based on the single harmonic system matrix A obtained in S20 and the measured magnetization signal U obtained in S30 , a solution model for the magnetic particle concentration is constructed, and the concentration is calculated using the Newton-Raphson iterative algorithm.

[0039] Furthermore, step S40 includes:

[0040] Step S41: construct a magnetic nanoparticle concentration distribution model based on the new single harmonic system matrix A and the magnetization signal U:

[0041] Ac=U

[0042] Where A is the new single harmonic system matrix, U is the measured magnetization signal, c is the concentration distribution of magnetic nanoparticles, and

[0043]

[0044] Step S42: Using the Newton-Raphson iterative algorithm, the spatial distribution of the concentrations of two different types of magnetic nanoparticles is calculated:

[0045] c k+1 =c k -(A T A+λI) -1 A T (A T c k -U)

[0046] Where k is the number of iterations, λ is the regularization factor, and I is the identity matrix.

[0047] The actual applicable scenario of the present invention is single harmonic two-color magnetic nanoparticle imaging, which is described here by taking single harmonic two-color magnetic nanoparticle imaging as an example.

[0048] First, using the magnetic nanoparticle imaging system, a certain imaging field of view and excitation intensity are set, and two different unit volume magnetic nanoparticle samples are placed at the zero magnetic field point respectively. The excitation magnetic field and scanning magnetic field are applied to the imaging field of view, and the single harmonic (such as the third harmonic) point spread function of the particle magnetization signal is extracted. Based on this, the single harmonic system matrices A1 and A2 of the two different magnetic particles are constructed.

[0049] The object to be measured is placed in a magnetic nanoparticle imaging system, the object to be measured is excited using the same excitation conditions, and its single harmonic (such as the third harmonic) is extracted to measure the magnetization signal U.

[0050] The single harmonic system matrices A1 and A2 of the two magnetic particles are horizontally spliced ​​to obtain a new single harmonic system matrix A.

[0051] A=[A1A2]

[0052] According to the single harmonic system matrix A and the measured magnetization signal U, a solution model for the magnetic particle concentrations c1 and c2 is constructed.

[0053] Ac=U

[0054] Where A is the new single harmonic system matrix, U is the measured magnetization signal, c is the concentration distribution of magnetic nanoparticles, and

[0055]

[0056] The Newton-Raphson iterative algorithm is used to solve the spatial distribution of the concentration of two different types of magnetic nanoparticles:

[0057] c k+1 =c k -(A T A+λI) -1 A T (A T c k -U)

[0058] Where k is the number of iterations, λ is the regularization factor, and I is the identity matrix.

[0059] The present invention proposes a dual-color magnetic nanoparticle imaging method based on a single harmonic system matrix. The method obtains the magnetization response spectrum of magnetic nanoparticles at different positions relative to the zero magnetic field point by scanning the zero magnetic field point, and extracts the single harmonic signal of the magnetization response spectrum to construct a single harmonic system matrix. This method maximizes the constraints on solving the concentration of the two magnetic nanoparticles, reduces the crosstalk of the concentration signals between different magnetic nanoparticles, and effectively improves the quantitative accuracy of dual-color magnetic nanoparticle imaging. It is of great significance to promote the application of magnetic nanoparticle imaging technology in clinical medicine.

[0060] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A dual-color magnetic nanoparticle imaging method based on a single harmonic system matrix, characterized in that: include: Based on two different types of magnetic nanoparticles, the two different types of magnetic nanoparticle samples are respectively moved to the central zero magnetic field point, a scanning magnetic field is applied to make the zero magnetic field point scan the entire imaging field of view, and an excitation magnetic field is applied to magnetize the magnetic nanoparticles, thereby obtaining magnetization spectrum signals of the two magnetic nanoparticle samples; wherein the magnetization spectrum signals are generated by different types of magnetic nanoparticles at different positions relative to the zero magnetic field point; based on the single harmonics of the magnetization spectrum signals of the magnetic nanoparticle samples, single harmonic system matrices A1 and A2 are constructed; Measuring the object to be measured composed of two types of magnetic nanoparticles to obtain a measured magnetization signal U; The system matrices A1 and A2 of two different types of magnetic nanoparticles are horizontally spliced ​​to obtain a new single harmonic system matrix A; The new single harmonic system matrix A is combined with the measured magnetization signal U to obtain two different types of magnetic nanoparticle concentration distributions c1 and c2, and the concentration distributions of these two magnetic particles are respectively sent to different color channels and displayed in different colors.

2. The dual-color magnetic nanoparticle imaging method based on a single harmonic system matrix according to claim 1, characterized in that: Obtaining the new single harmonic system matrix A includes: A=[A1 A2] Among them, A1 and A2 are the single harmonic system matrices of the first magnetic nanoparticle sample and the second magnetic nanoparticle sample respectively.

3. The dual-color magnetic nanoparticle imaging method based on a single harmonic system matrix according to claim 1, characterized in that: Obtaining the concentration distributions of the two different types of magnetic nanoparticles includes: According to the new single harmonic system matrix A and the measured magnetization signal U, a solution model for the magnetic nanoparticle concentration distribution c1 and c2 is constructed; The two magnetic nanoparticle concentration distributions c1 and c2 are iteratively reconstructed to solve the spatial distribution of the concentrations of two different types of magnetic nanoparticles.

4. The dual-color magnetic nanoparticle imaging method based on a single harmonic system matrix according to claim 3, characterized in that: Constructing the magnetic nanoparticle concentration distribution model includes: Ac=U Where A is the new single harmonic system matrix, U is the measured magnetization signal, c is the concentration distribution of magnetic nanoparticles, and 5. The dual-color magnetic nanoparticle imaging method based on a single harmonic system matrix according to claim 3, characterized in that: Solving the spatial distribution of the concentrations of two different types of magnetic nanoparticles involves: c k+1 =c k -(A T A+λI) -1 A T (A T c k -U) Where k is the number of iterations, λ is the regularization factor, and I is the identity matrix.

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