International Journal on Magnetic Particle Imaging (IJMPI)
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Measurement of magnetic relaxation in intratumor magnetic nanoparticles
No full textThe magnetization response such as magnetic relaxation of magnetic nanoparticles was affected by the intratumor multiple environments. In this study, the intratumor magnetic relaxation was measured, and the magnetic relaxation time was analyzed to evaluate the environment of a living tumor. The estimated distribution of the magnetic relaxation time in tumor was different from those in the non-biological samples such as magnetic nanoparticle dispersed in liquid and solidified conditions. The evaluation of the magnetic relaxation time particularly determined by the Brownian relaxation associated with the particle physical rotation of intratumor magnetic nanoparticles develops a low-invasive tissue imaging technique based on the magnetic particle imaging
A novel method for magnetic nanoparticles deep optical imaging using SPAD
No full textThis paper proposes a novel magneto-optical imaging method that utilizes the superparamagnetic and optical properties of magnetic nanoparticles (MNPs). By measuring the rotation angle of linearly polarized light passing through MNPs under an external alternating magnetic field via the Faraday effect, we address the issue of optical signal attenuation in deep biological tissue imaging. We introduce a single-photon avalanche diode (SPAD) to detect extremely weak optical signals. Experimental results show that the harmonic signals of the Faraday rotation angle are linearly related to MNPs concentration. Under conditions with thick phantoms simulating deep tissue in the optical path, SPAD can still effectively detect polarization characteristics, verifying the feasibility of using the magneto-optical effect for high-resolution in vivo detection and imaging of deep biological tissues. This provides an exciting possibility for achieving high-resolution in vivo detection and imaging of deep biological tissues in the future
Preclinical Open-Sided Magnetic Particle Imaging Scanner
No full textPreclinical magnetic particle imaging (MPI) plays a crucial role in advancing biomedical research through in vivo studies and helps with the translation into clinical systems. Our previously developed open-sided MPI system was capable of electronic rotation and translation of the field-free line (FFL) in three dimensions. However, the field of view (FOV) was limited to 34 x 18 x 12 mm3 due to restrictions of the drive and receive coils. Here we introduce, a preclinical MPI system with a FOV of 100 x 50 x 25 mm3, which is suitable for tumor imaging in small mice. We present the imaging system design and 2D imaging results of the phantom obtained using the developed scanner
High Performance MPI with Magnetically induced Magnetosome Chains (MAGiCs)
No full textIn this study, we demonstrate the potential of magnetically induced magnetosome chains (MAGiCs), which are composed of biosynthesized magnetic nanoparticles (MNPs), as the traces for magnetic particle imaging (MPI). The magnetosomes in MAGiC align in an orderly manner under the induction of a uniform magnetic field, and in this state, MAGiC can significantly enhance the MPI imaging quality. MPS result showed that compared to the commercial tracer VivoTrax+, MAGiC achieved a 25-fold improvement in resolution and a 91-fold increase in signal intensity. In 2D MPI, the reconstructed images achieved a resolution of 0.3 mm under a 1.25 T/m gradient field. All images were reconstructed using the x-space algorithm without employing iterative algorithms
A trace doping strategy for developing magnetic nanoparticles magnetic particle imaging and magnetic hyperthermia properties
No full textMagnetic particle imaging-guided magnetic hyperthermia therapy (MPI-MHT) allows direct imaging, quantification and prediction of heat production of magnetic nanoparticles at focal sites, guiding target mapping, dose planning and efficacy monitoring of subsequent magnetic hyperthermia therapy, which greatly improves the safety and effectiveness of magnetic hyperthermia therapy. However, due to the performance contradiction between magnetothermal therapy and MPI itself, the currently available magnetic particles fail to balance the needs of both in performance regulation, which greatly hinders the construction of MPI-MHT integrated platform. In this work, we proposed a trace doping strategy to synthesize the magnetic spin ordered and anisotropic tunable nanoprobes. It has been tested to demonstrate unprecedented MPI-MHT capability. It brings great prospects for the construction of MPI-MHT integrated diagnosis and treatment platform, effectively avoiding the harm caused by the increased burden of over-diagnosis and over-treatment
TrainingPhantoms.jl: Simple and Versatile Image Phantom Generation
No full textLarge collections of labeled data play a crucial role in supervised machine learning projects. Unfortunately, such datasets are quite rare in the medical domain. In this work, the Julia project TrainingPhantoms.jl is introduced, which provides a simple interface to generate large and diverse collections of randomly generated image phantoms. The proposed phantom generator has been successfully used to train an image quality enhancement network that managed to generalize to unseen experimental out-of-distribution data
The Simulation of a magnetic particle optical imaging system for biological tissues
No full textBiomedical imaging, as an emerging interdisciplinary field, is an essential tool that bridges basic biomedical research and clinical diagnosis and treatment. Traditional biological imaging methods face certain biocompatibility issues, while optical biological imaging techniques struggle to overcome challenges related to imaging depth. However, magnetic nanoparticles (MNPs), due to their non-toxicity and unique magnetic properties, have emerged as promising contrast agents for biological imaging. We propose a novel ultrafast optical imaging device based on MNPs, with the high power of the femtosecond laser, it is possible to image MNPs at greater depths within biological tissues under the influence of an external magnetic field. Simulation results validate the feasibility of this device. It can improve the effects of strong scattering and absorption in tissues, thereby enhancing the penetration of light into biological tissues, with the potential for further increasing imaging depth by varying the wavelength
Neural implicit representations for grid-agnostic MPI reconstructions
No full textMagnetic particle imaging (MPI) reconstructs the spatial distribution of magnetic nanoparticles on a fixed grid, the resolution of which is limited by the noise present in the system. This paper addresses the reconstruction problem while integrating single-image super-resolution for concentration maps. We introduce Neural Implicit Representations (NIR) as an image prior, enabling arbitrary grid size sampling after training. Experimental results using a spiral phantom measurement reveal that NIR-based reconstruction maintains image sharpness across diverse grid sizes, surpassing the two-stage Kaczmarz-L2 reconstruction followed by bicubic up-sampling in preserving fine structural details. This technique has a potential for high-resolution MPI imaging without relying on extensive datasets
Simulation of Multi-Coil Single-Sided MPI System with Offset Field Spatial Encoding
No full textSingle-sided Magnetic particle imaging (MPI) systems have great potential for clinical applications because it concentrates all hardware on one side, allowing for an unrestricted imaging volume. However, the non-uniform magnetic field distribution in single-sided MPI devices poses challenges for generating high gradient selection fields. To address this, we developed a new offset field spatial encoding technique that combines amplitude modulation technology within a multi-coil structure, enabling 3D imaging without the need for classical selection fields and mechanical movement scanning. In simulation experiments, we validated the feasibility of this design, and the results indicate that the single-sided MPI device based on multi-coil amplitude modulation technology has the potential to achieve high spatial resolution and high temporal resolution
Spatial encoding with receive coils in MPI
No full textMPI techniques traditionally use gradient magnetic fields for spatial encoding. Despite their proven efficiency, these methods are power-intensive and technically challenging to implement on a human scale. In this work, we explore the potential for spatial encoding of superparamagnetic nanoparticle distributions using only a drive field and an array of receiving coils with unique spatial sensitivity profiles. We demonstrate the feasibility of this concept using a prototype 1D imaging system extended to 2D by mechanically moving the sample. The proposed approach permits high-speed gradient-free data acquisition for rapid imaging but also has some limitations in terms of penetration depth