scholarly journals Magnetic particle imaging of magnetotactic bacteria as living contrast agents is improved by altering magnetosome structures

2021 ◽  
Author(s):  
Ashley V. Makela ◽  
Melissa A. Schott ◽  
Cody Madsen ◽  
Emily Greeson ◽  
Christopher H. Contag
Keyword(s):  
Contrast Agents ◽  
Iron Nanoparticles ◽  
Magnetic Particle ◽  
Multimodality Imaging ◽  
Imaging Modality ◽  
Biological Effects ◽  
Magnetotactic Bacteria ◽  
Magnetic Particle Imaging ◽  
Linear Chains ◽  
Particle Imaging

ABSTRACTIron nanoparticles used as imaging contrast agents can help differentiate between normal and diseased tissue, or track cell movement and localize pathologies. Magnetic particle imaging (MPI) is an imaging modality that uses the magnetic properties of iron nanoparticles to provide specific, quantitative and sensitive imaging data. MPI signals depend on the size, structure and composition of the nanoparticles; MPI-tailored nanoparticles have been developed by modifying these properties. Magnetotactic bacteria produce magnetosomes which mimic synthetic nanoparticles, and thus comprise a living contrast agent in which nanoparticle formation can be modified by mutating genes. Specifically, genes that encode proteins critical to magnetosome formation and regulation, such as mamJ which helps with filament turnover. Deletion of mamJ in Magnetospirillum gryphiswaldense, MSR-1 led to clustered magnetosomes instead of the typical linear chains. Here we examined the effects of this magnetosome structure and revealed improved MPI signal and resolution from clustered magnetosomes compared to linear chains. Bioluminescent MSR-1 with the mamJ deletion were injected intravenously into tumor-bearing and healthy mice and imaged using both in vivo bioluminescence imaging (BLI) and MPI. BLI revealed the location and viability of bacteria which was used to validate localization of MPI signals. BLI identified the viability of MSR-1 for 24 hours and MPI detected iron in the liver and in multiple tumors. Development of living contrast agents offers new opportunities for imaging and therapy by using multimodality imaging to track the location and viability of the therapy and the resulting biological effects.

scholarly journals Magnetic particle imaging of particle dynamics in complex matrix systems

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sebastian Draack ◽  
Meinhard Schilling ◽  
Thilo Viereck
Keyword(s):  
Magnetic Particle ◽  
Imaging Modality ◽  
Three Dimensional ◽  
Local Environment ◽  
Relaxation Mechanism ◽  
Harmonic Spectrum ◽  
Magnetic Particle Imaging ◽  
Matrix Interactions ◽  
Tracer Distribution ◽  
Particle Imaging

Abstract Magnetic particle imaging (MPI) is a young imaging modality for biomedical applications. It uses magnetic nanoparticles as a tracer material to produce three-dimensional images of the spatial tracer distribution in the field-of-view. Since the tracer magnetization dynamics are tied to the hydrodynamic mobility via the Brownian relaxation mechanism, MPI is also capable of mapping the local environment during the imaging process. Since the influence of viscosity or temperature on the harmonic spectrum is very complicated, we used magnetic particle spectroscopy (MPS) as an integral measurement technique to investigate the relationships. We studied MPS spectra as function of both viscosity and temperature on model particle systems. With multispectral MPS, we also developed an empirical tool for treating more complex scenarios via a calibration approach. We demonstrate that MPS/MPI are powerful methods for studying particle-matrix interactions in complex media.

scholarly journals Introducing a frequency-tunable magnetic particle spectrometer

2015 ◽  
Vol 1 (1) ◽  
pp. 249-253 ◽  
Author(s):  
André Behrends ◽  
Matthias Graeser ◽  
Thorsten M. Buzug
Keyword(s):  
Magnetic Nanoparticles ◽  
Image Quality ◽  
Magnetic Particle ◽  
Imaging Modality ◽  
Magnetic Particle Imaging ◽  
Common Technique ◽  
Frequency Tunable ◽  
Excitation Frequencies ◽  
Particle Imaging

AbstractImage quality in the new imaging modality magnetic particle imaging (MPI) heavily relies on the quality of the magnetic nanoparticles in use. Therefore, it is crucial to understand the behaviour of such particles. A common technique to analyze the behaviour of the particles is magnetic particle spectrometry (MPS). However, most spectrometers are limited to measurements at a single or multiple discrete excitation frequencies. This paper introduces a frequency-tunable spectrometer, able to perform measurements in the range of 100 Hz - 24kHz.

scholarly journals Sequences for real-time magnetic particle imaging

2015 ◽  
Vol 1 (1) ◽  
pp. 353-355
Author(s):  
Matthias Weber ◽  
Klaas Bente ◽  
Anselm von Gladiss ◽  
Matthias Graeser ◽  
Thorsten M. Buzug
Keyword(s):  
Real Time ◽  
Magnetic Particle ◽  
Imaging Modality ◽  
Complex Field ◽  
Encoding Scheme ◽  
Imaging Capability ◽  
Magnetic Particle Imaging ◽  
Temporal And Spatial ◽  
Particle Imaging ◽  
Higher Sensitivity

AbstractMagnetic Particle Imaging (MPI) is a new imaging modality with the potential to be a new medical tool for angiographic diagnostics. It is capable of visualizing the spatial distribution of super-paramagnetic nanoparticles in high temporal and spatial resolution. Furthermore, the new spatial encoding scheme of a field free line (FFL) promises a ten-fold higher sensitivity. So far, all know imaging devices featuring this new technique feature slow data acquisition and thus, are far away from real-time imaging capability. An actual real-time approach requires a complex field generator and an application of currents with very precise amplitude and phase. Here, we present the first implementation and calibration of a dynamic FFL field sequence enabling the acquisition of 50 MPI images per second in a mouse sized scanner.

scholarly journals In vivo multimodal magnetic particle imaging (MPI) with tailored magneto/optical contrast agents

Biomaterials ◽  
2015 ◽  
Vol 52 ◽  
pp. 251-261 ◽  
Author(s):  
Hamed Arami ◽  
Amit P. Khandhar ◽  
Asahi Tomitaka ◽  
Elaine Yu ◽  
Patrick W. Goodwill ◽  
...  
Keyword(s):  
Contrast Agents ◽  
Magnetic Particle ◽  
Optical Contrast ◽  
Optical Contrast Agents ◽  
Magnetic Particle Imaging ◽  
Particle Imaging

scholarly journals Magnetic Particle Imaging: Current and Future Applications, Magnetic Nanoparticle Synthesis Methods and Safety Measures

2021 ◽  
Vol 22 (14) ◽  
pp. 7651
Author(s):  
Caroline Billings ◽  
Mitchell Langley ◽  
Gavin Warrington ◽  
Farzin Mashali ◽  
Jacqueline Anne Johnson
Keyword(s):  
Magnetic Particle ◽  
Tumor Imaging ◽  
Imaging Modality ◽  
Nanoparticle Synthesis ◽  
Superparamagnetic Iron Oxide ◽  
Synthesis Methods ◽  
Iron Oxide Particles ◽  
Magnetic Particle Imaging ◽  
Wide Range ◽  
Particle Imaging

Magnetic nanoparticles (MNPs) have a wide range of applications; an area of particular interest is magnetic particle imaging (MPI). MPI is an imaging modality that utilizes superparamagnetic iron oxide particles (SPIONs) as tracer particles to produce highly sensitive and specific images in a broad range of applications, including cardiovascular, neuroimaging, tumor imaging, magnetic hyperthermia and cellular tracking. While there are hurdles to overcome, including accessibility of products, and an understanding of safety and toxicity profiles, MPI has the potential to revolutionize research and clinical biomedical imaging. This review will explore a brief history of MPI, MNP synthesis methods, current and future applications, and safety concerns associated with this newly emerging imaging modality.

scholarly journals Development of Magnetic Particle Imaging (MPI) for Cell Tracking and Detection

2020 ◽  
Author(s):  
Kierstin P Melo ◽  
Ashley V Makela ◽  
Natasha N Knier ◽  
Amanda M Hamilton ◽  
Paula J Foster
Keyword(s):  
Iron Content ◽  
Cell Tracking ◽  
Magnetic Particle ◽  
Ex Vivo ◽  
Imaging Modality ◽  
Superparamagnetic Iron Oxide ◽  
Cell Injection ◽  
Magnetic Particle Imaging ◽  
Particle Imaging

AbstractIntroductionMagnetic particle imaging (MPI) is a new imaging modality that sensitively and specifically detects superparamagnetic iron oxide nanoparticles (SPIONs) within a sample. SPION-based MRI cell tracking has very high sensitivity, but low specificity and quantification of iron labeled cells is difficult. MPI cell tracking could overcome these challenges.MethodsMDM-AB-231BR cells labeled with MPIO, mice were intracardially injected with either 2.5 × 105 or 5.0 × 105 cells. MRI was performed in vivo the same day at 3T using a bSSFP sequence. After mice were imaged ex vivo with MPI. In a second experiment Mice received an intracardiac injection of either 2.5 × 10 5 or 5 × 10 4 MPIO-labeled 231BR cells. In a third experiment, mice were injected with 5 × 10 4 4T1BR cells, labelled with either MPIO or the SPION Vivotrax. MRI and MPI was performed in vivo.ResultsSignal from MPI and signal voids from MRI both showed more iron content in mice receiving an injection of 5.0 × 105 cells than the 2.5 × 105 injection. In the second experiment, Day 0 MRI showed signal voids and MPI signal was detected in all mouse brains. The MPI signal and iron content measured in the brains of mice that were injected with 2.5 × 10 5 cells were approximately four times greater than in brains injected with 5 × 10 4 cells. In the third experiment, in vivo MRI was able to detect signal voids in the brains of mice injected with Vivotrax and MPIO, although voids were fainter in Vivotrax labeled cells. In vivo MPI signal was only detectable in mice injected with MPIO-labeled cells.ConclusionThis is the first example of the use of MPIO for cell tracking with MPI. With an intracardiac cell injection, approximately 15% of the injected cells are expected to arrest in the brain vasculature. For our lowest cell injection of 5.0 × 104 cells this is ∼10000 cells.

scholarly journals Magnetic-field measurement and simulation of a field-free line magnetic-particle scanner

2017 ◽  
Vol 3 (2) ◽  
Author(s):  
Jan Stelzner ◽  
Thorsten M. Buzug
Keyword(s):  
Magnetic Field ◽  
Spatial Distribution ◽  
Magnetic Particle ◽  
Imaging Modality ◽  
Magnetic Field Measurement ◽  
Magnetic Particle Imaging ◽  
Particle Imaging ◽  
Harmful Radiation ◽  
The Magnetic Field ◽  
Magnetization Behavior

AbstractIn 2005, B. Gleich and J. Weizenecker initially presented the tracer based medical imaging modality Magnetic Particle Imaging (MPI). It uses the nonlinear magnetization behavior of super paramagnetic iron oxide nanoparticles (SPIONs). MPI has the potential to perform real-time imaging in the sub millimeter-range without the use of harmful radiation. To acquire a particle signal from the tracer, an alternating homogenous magnetic field (drive field) is applied. Due to the nonlinearity of the particle magnetization, the magnetic field is distorted and higher harmonics are generated that indicate a particle concentration within the field of view (FOV). For the spatial distribution, another magnetic field that exhibits a high gradient (selection field) is applied simultaneously. Basically, there are two different types of selection fields containing either a field- free point (FFP) or a field-free line (FFL). Because of magnetic saturation, only SPIONs within the close vicinity of the FFP or FFL contribute to the particle signal. As the FFP is moved by the drive field through the FOV a spatial distribution of the SPIONs can be obtained. In the other encoding concept, the FFL rotates and is additionally translated by the drive field to obtain one dimensional projections for various angles. In this work, the currently world’s largest FFL MPI Scanner is investigated. Single components of the generated magnetic field are measured precisely to accomplish an accurate simulation of a translating and rotating FFL.

scholarly journals A perspective on a rapid and radiation-free tracer imaging modality, magnetic particle imaging, with promise for clinical translation

2018 ◽  
Vol 91 (1091) ◽  
pp. 20180326 ◽  
Author(s):  
Prashant Chandrasekharan ◽  
Zhi Wei Tay ◽  
Xinyi Yedda Zhou ◽  
Elaine Yu ◽  
Ryan Orendorff ◽  
...  
Keyword(s):  
Magnetic Particle ◽  
Imaging Modality ◽  
Clinical Translation ◽  
Magnetic Particle Imaging ◽  
Tracer Imaging ◽  
Particle Imaging

scholarly journals Artifacts in field free line magnetic particle imaging in the presence of inhomogeneous and nonlinear magnetic fields

2015 ◽  
Vol 1 (1) ◽  
pp. 245-248
Author(s):  
Hanne Medimagh ◽  
Patrick Weissert ◽  
Gael Bringout ◽  
Klaas Bente ◽  
Matthias Weber ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Image Reconstruction ◽  
Magnetic Fields ◽  
Magnetic Particle ◽  
Imaging Modality ◽  
System Function ◽  
Magnetic Particle Imaging ◽  
Gradient Fields ◽  
Particle Imaging ◽  
The Magnetic Field

AbstractIntroduction: Magnetic Particle Imaging (MPI) is an emerging medical imaging modality that detects super-paramagnetic particles exploiting their nonlinear magnetization response. Spatial encoding can be realized using a Field Free Line (FFL), which is generated, rotated and translated through the Field of View (FOV) using a combination of magnetic gradient fields and homogeneous excitation fields. When scaling up systems and/or enlarging the FOV in comparison to the scanner bore, ensuring homogeneity and linearity of the magnetic fields becomes challenging. The present contribution describes the first comprehensive, systematic study on the influence of magnetic field imperfections in FFL MPI. Methods: In a simulation study, 14 different FFL scanner setups have been examined. Starting from an ideal scanner using perfect magnetic fields, defined imperfections have been introduced in a range of configurations (nonlinear gradient fields, inhomogeneous excitation fields, or inhomogeneous receive fields, or a combination thereof). In the first part of the study, the voltage induced in the receive channels parallel and perpendicular to the FFL translation have been studied for discrete FFL angles. In the second part, an imaging process has been simulated comparing different image reconstruction approaches. Results: The induced voltage signals demonstrate illustratively the effect of the magnetic field imperfections. In images reconstructed using a Radon-based approach, the magnetic field imperfections lead to pronounced artifacts, especially if a deconvolution using the point spread function is performed. In images reconstructed using a system function based approach, variations in local image quality become visible. Conclusion: For Radon-based image reconstruction in FFL MPI in the presence of inhomogeneous and nonlinear magnetic fields, artifact correction methods will have to be developed. In this regard, a first approach has recently been presented by another group. Further research is required to elucidate the influence of magnetic field imperfections in MPI using a system function based approach.

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