Simulation Of Magnetic Particle Imaging Using Rotational Brownian Dynamics Simulations

Magnetic Particle Imaging (MPI) is an emerging biomedical imaging technique which uses the non-linear magnetization characteristics of magnetic nanoparticle tracers to obtain millimeter scale temporal and spatial resolution images. Human tissue, being diamagnetic, does not produce a background signal, meaning that the images have near-perfect contrast. Theoretical models assume the magnetic dipoles of nanoparticles used as tracers instantaneously align with the applied field which is at odds with the experimental results showing that finite relaxation affects the signal and resolution of the image. We model this relaxation effect using rotational Brownian dynamics simulations to predict the effect on the resolution and account for the shift in image location. We model the behavior of nanoparticles in response to the rapid movement of a field free point (FFP), which leads to the flipping of the saturated nanoparticles inducing a voltage in the receiving coil. The magnetic dipoles lag behind the changing field due to relaxation and hence produce a significant difference in the signal properties. We also model the magnetic particle relaxometer which is used to measure properties of tracer material by applying an oscillating field to the suspension of nanoparticles The study demonstrates the effect of Brownian relaxation on the signal strength, resolution, and image shift distance.

This volume provides a comprehensive overview of recent developments in magnetic particle imaging (MPI), a novel imaging modality. Using various static and oscillating magnetic fields, and tracer materials made from iron oxide nanoparticles, MPI can perform background-free measurements of the particles’ local concentration. The method exploits the nonlinear remagnetization behavior of the particles and has the potential to surpass current methods for the detection of iron oxide in terms of sensitivity and spatiotemporal resolution. Starting from an introduction to the technology, the topics addressed include setting up an imaging device, assessment of image quality, development of new MPI tracer materials, and the first preclinical results. This is the first book to be published on magnetic particle imaging, and it will be an invaluable source of information for everyone with an interest in this exciting new modality.

Offering the latest information in magnetic nanoparticle (MNP) research, Magnetic Nanoparticles: From Fabrication to Clinical Applications provides a comprehensive review, from synthesis, characterization, and biofunctionalization to clinical applications of MNPs, including the diagnosis and treatment of cancers.This book, written by some of the mo

This open access book, published in the Soft and Biological Matter series, presents an introduction to selected research topics in the broad field of flowing matter, including the dynamics of fluids with a complex internal structure -from nematic fluids to soft glasses- as well as active matter and turbulent phenomena. Flowing matter is a subject at the crossroads between physics, mathematics, chemistry, engineering, biology and earth sciences, and relies on a multidisciplinary approach to describe the emergence of the macroscopic behaviours in a system from the coordinated dynamics of its microscopic constituents. Depending on the microscopic interactions, an assembly of molecules or of mesoscopic particles can flow like a simple Newtonian fluid, deform elastically like a solid or behave in a complex manner. When the internal constituents are active, as for biological entities, one generally observes complex large-scale collective motions. Phenomenology is further complicated by the invariable tendency of fluids to display chaos at the large scales or when stirred strongly enough. This volume presents several research topics that address these phenomena encompassing the traditional micro-, meso-, and macro-scales descriptions, and contributes to our understanding of the fundamentals of flowing matter. This book is the legacy of the COST Action MP1305 “Flowing Matter”.

Magnetic Nanoparticles in Human Health and Medicine Explores the application of magnetic nanoparticles in drug delivery, magnetic resonance imaging, and alternative cancer therapy Magnetic Nanoparticles in Human Health and Medicine addresses recent progress in improving diagnosis by magnetic resonance imaging (MRI) and using non-invasive and non-toxic magnetic nanoparticles for targeted drug delivery and magnetic hyperthermia. Focusing on cancer diagnosis and alternative therapy, the book covers both fundamental principles and advanced theoretical and experimental research on the magnetic properties, biocompatibilization, biofunctionalization, and application of magnetic nanoparticles in nanobiotechnology and nanomedicine. Chapters written by a panel of international specialists in the field of magnetic nanoparticles and their applications in biomedicine cover magnetic hyperthermia (MHT), MRI contrast agents, biomedical imaging, modeling and simulation, nanobiotechnology, toxicity issues, and more. Readers are provided with accurate information on the use of magnetic nanoparticles in diagnosis, drug delivery, and alternative cancer therapeutics—featuring discussion of current problems, proposed solutions, and future research directions. Topics include current applications of magnetic iron oxide nanoparticles in nanomedicine and alternative cancer therapy: drug delivery, magnetic resonance imaging, superparamagnetic hyperthermia as alternative cancer therapy, magnetic hyperthermia in clinical trials, and simulating the physics of magnetic particle heating for cancer therapy. This comprehensive volume: Covers both general research on magnetic nanoparticles in medicine and specific applications in cancer therapeutics Discusses the use of magnetic nanoparticles in alternative cancer therapy by magnetic and superparamagnetic hyperthermia Explores targeted medication delivery using magnetic nanoparticles as a future replacement of conventional techniques Reviews the use of MRI with magnetic nanoparticles to increase the diagnostic accuracy of medical imaging Magnetic Nanoparticles in Human Health and Medicine is a valuable resource for researchers in the fields of nanomagnetism, magnetic nanoparticles, nanobiomaterials, nanobioengineering, biopharmaceuticals nanobiotechnologies, nanomedicine, and biopharmaceuticals, particularly those focused on alternative cancer diagnosis and therapeutics.

Marlitt Erbe provides a detailed introduction into the young research field of Magnetic Particle Imaging (MPI) and field free line (FFL) imaging in particular. She derives a mathematical description of magnetic field generation for FFL imaging in MPI. To substantiate the simulation studies on magnetic FFL generation with a proof-of-concept, the author introduces the FFL field demonstrator, which provides the world’s first experimentally generated rotated and translated magnetic FFL field complying with the requirements for FFL reconstruction. Furthermore, she proposes a scanner design of considerably enhanced magnetic field quality and efficiency. The author discusses the influence of magnetic field quality optimization on the image quality achieved using efficient Radon-based reconstruction methods, which arise for a line detection scheme and based on this optimized design, presents a dynamic FFL scanner assembly.

A new tomographic imaging modality called magnetic particle imaging (MPI) has been proposed in 2005. Using the non-linear magnetization curve of specific nanoparticles, a detectable signal proportional to the concentration of these particles can be generated. For medical imaging the tracer material can be injected into the blood system. Due to fast image acquisition, not only morphological, but also functional imaging is possible. The feasibility of medical imaging with this technique could be demonstrated at real time imaging of a beating mouse heart. Spatial encoding is provided by superimposing dedicated external magnetic fields. For the resulting shape of this field a field free line has been proposed. This work presents the implementation of the MPI system with a discretely rotatable and dynamically translatable field free line.

This book presents the most important and main concepts of the molecular and microsimulation techniques. It enables readers to improve their skills in developing simulation programs by providing physical problems and sample simulation programs for them to use.