Selection field generation for an open aperture field free line magnetic particle imaging scanner
Can Barış Top
We present the design and measurement results for the selection field generation of an open scanner configuration for field free line (FFL) magnetic particle imaging. The FFL can be rotated electronically using the designed coils. The selection of the imaging plane is possible by asymmetrical excitation of the upper and lower coil groups. The gradient of the magnetic field is orthogonal to its gradient, allowing 2D scan using a single drive coil channel. The mechanical housing of the coils are manually adjustable to provide the highest gradient level for the imaged object size. In the current configuration, a magnetic field gradient between 0.5 T/m - 0.74 T/m can be generated in a 60 mm diameter field of view.
Submillimeter magnetic particle imaging with low symmetrical field gradient
Yasushi Takemura, Suko Bagus Trisnanto
Magnetic particle imaging (MPI) requires high field gradient to acquire sharp point spread function used to refine spatial resolution for submillimeter imaging of cells and small animal models. Since the steep field gradient potentially causes difficulty in the sample handling and the signal processing, minimizing the field gradient is more practical even though it degrades the spatial resolution. By modulating relaxation responses of magnetic nanotracers at two distinctive frequencies: 2 kHz and 1MHz, we reconstructed images of Resovist® sample placed in a 1.4×1.4 mm2 field of view. This modulated MPI implements 2 sets of permanent magnets of which the same polarity faces one another to create a 2 Tm-1 symmetrical field gradient on the xy plane and 3 Tm-1 on the z axis. Although the spatial resolution appears poor to differentiate two-neighboring circular phantoms of dense liquid samples, we could visualize a 1-mm ring-shaped solid sample with 0.1 mm thickness.
Gradient power reducing using pulsed selection-field sequences
Florian Thieben, Marija Boberg, Patryk Szwargulski, Matthias Graeser, Tobias Knopp
Large selection-field power is required to generate a sufficient gradient strength in Magnetic Particle Imaging (MPI). Without cooling, the subsequent heat generation can limit the maximum experiment time. For commercially available MPI scanners a lot of effort was put into active cooling requiring space and infrastructure to dissipate heat. In this abstract, a promising power handling for the selection-field generation is presented. Using a pulsed instead of a continuous selection-field the gradient strength can be increased and no active cooling is required.
Design of A Rabbit Scale 3D Magnetic Particle Imaging System with Amplitude Modulation
Tuan-Anh Le, Minh Phu Bui, Jungwon Yoon
Magnetic Particle Imaging (MPI) is a fast and sensitive imaging method that can be used to measure the spatial distribution of superparamagnetic iron oxide (SPIO) nanoparticles. To overcome some limitations of general MPI, the Amplitude Modulation MPI (AM MPI), which uses a low-amplitude excitation field combined with a low-frequency drive field, was suggested. In this paper, we present the design of a rabbit scale 3D AM MPI system with a larger bore size (9 cm). The AM MPI can reach a drive-field field-of-view (DF-FOV) of 4.00 x 4.00 x 8.00 cm and a whole field-of-view (W-FOV) of 6.36 x 6.36 x 8.00 cm at 2.2 T/m.
Spatial selectivity enhancement in RF-hyperthermia by magnetic flux confinement
Kulthisa Sajjamark, Jochen Franke, Rainer Pietig, Heinrich Lehr, Volker Niemann
Aiming to increase spatial selectivity which provides the precision in hyperthermia therapy and high resolution in imaging, we propose a strategy to increase field gradient for Magnetic Particle Imaging (MPI) modality. In this study, a solution for an existing MPI system topology was simulated, which uses additional soft magnetic material as iron core retrofit at the center of selection field coil. Due to core property of high magnetic permeability relative to air, magnetic flux gets confined to increase selection field gradient field slope. Within this simulation study, the optimal core position is evaluated whilst its effects on the magnet system is validated. We found that this technique increases the magnetic field gradient up to a factor of 1.4 from 2.5 T/m to 3.4 T/m in z-direction, without significant loading of the drive field resonance circuit due to power losses caused by eddy currents in the MPI compatible iron core shielding.
Initial imaging experiments with a direct-driven relaxation Magnetic Particle Imaging setup
Thilo Viereck, Sebastian Draack, Melvin Kuester, Meinhard Schilling, Frank Ludwig
This contribution presents initial imaging experiments with a newly designed imaging setup that facilitates Magnetic Particle Imaging (MPI) by recording the step response of the tracer in contrast to its higher harmonic spectrum. Such a concept promises a greatly reduced complexity in hardware and enables a much simpler time-domain evaluation of the receive signals. The concept borrows from magnetorelaxometry (MRX) subjecting the tracer to a step change in excitation field to affect a relaxation of the particles’ magnetization. For that reason, all experience from MRX data evaluation and modeling of the magnetization response apply to the imaging variant as well. The hardware design of the system opens a great deal of flexibility regarding excitation patterns and signal evaluation for future experiments.
Session 2
Image Reconstruction 1
Multi-dimensional Harmonic Dispersion X-space MPI
Semih Kurt, Vagif Abdulla, Emine Ulku Saritas
In magnetic particle imaging (MPI), standard x-space reconstruction requires partial field-of-view (pFOV) processing steps: speed compensation of the received signal and gridding the non-equidistant field free point (FFP) positions to a Cartesian grid. Moreover, due to direct feedthrough filtering, a DC recovery algorithm must be utilized, which requires pFOVs to overlap with each other. In this work, we propose an alternative x-space reconstruction technique that does not require pFOV processing or overlapping pFOVs. The proposed technique is applicable to rapid and sparse multi-dimensional scanning trajectories where standard x-space reconstruction cannot be applied due to non-overlapping pFOVs.
Tailored regularization methods for multi-contrast magnetic particle imaging
Christina Brandt, Inga Glöckner, Martin Möddel, Tobias Knopp
Multi-contrast magnetic particle imaging (MPI) enables the determination of different contrasts in addition to the particle concentration. For instance it is possible to discriminate multiple tracer types that differ e.g. in the particle core size. One challenge of multi-contrast MPI is that the reconstruction problem is severely ill-posed such that in practice a perfect separation of different tracer types is not achieved. In this work, we develop a method for improving the channel separation and in turn prevent leakage from one channel into the other. Our approach exploits sparsity in both the spatial and the channel dimension. By developing a tailor regularization approach for improved multi-contrast reconstruction, we show that it is possible to significantly reduce signal leakage.
A sparse row-action algorithm for Magnetic Particle Imaging
Florian Lieb, Tobias Knopp
The image reconstruction in Magnetic Particle Imaging (MPI) relies on efficiently solving an ill-posed inverse problem. Current state-of-the-art reconstruction methods are either based on row-action methods with fast convergence but limited noise suppression or advanced sparsity constraints showing better image quality, but suffering from a higher computational complexity and slower convergence. In this contribution, we propose a novel row-action framework where advanced sparsity constraints, e.g., a combination of L1- and TV-norm, can be included. Its performance is numerically evaluated on simulated and real MPI data, showing a significant reduction of computation time while retaining the enhanced imaging quality.
Session 3
Nanoparticle Physics and Theory + Image Reconstruction
Towards accurate modeling of the multidimensional MPI physics
Tobias Kluth, Patryk Szwargulski, Tobias Knopp
The MPI image reconstruction problem requires, particularly for 2D and 3D excitation patterns, a measured system matrix due to the lack of an accurate model that is capable of describing the nanoparticles’ magnetization behavior in the MPI setup. Here we exploit a model based on Néel rotation for large particle ensembles and we find model parameters that describe measured 2D MPI data with much higher precision than state of the art MPI models, which is also illustrated in phantom experiments. This is a short summary of the recent work [4] to which we refer to for all further details.
A novel representation of the MPI system function
Marco Maass, Christine Droigk, Alfred Mertins
In a recent publication, based on the Langevin model, the exact mathematical relationship between the system function and tensor products of Chebyshev polynomials of second kind has been derived for the case in which multidimensional excitation is used for magnetic particle imaging. There, a new expression for the system function in magnetic particle imaging was derived. To make this representation easily accessible, the present paper focusses on the more practical aspects of the theory without going deep into the mathematical proofs. In particular, we examine the contribution of the mixing factors to the total energy of a system function component.
MNPDynamics: A computational toolbox for simulating magnetic moment behavior of ensembles of nanoparticles
Hannes Albers, Tobias Kluth, Tobias Knopp
In the context of system function modeling for magnetic particle imaging, computing fast and accurate approximations to the time evolution of magnetic nanoparticles' (MNPs) mean magnetic moment is a problem of interest. In a software toolbox we comprise algorithms and methods that can simulate Brownian and Néel rotation of MNPs' magnetic moments that can be used to obtain more accurate model-based system matrices than those relying on the so-called equilibrium model. We present and discuss results obtained with these implementations which are made available in the software toolbox under github.com/MagneticParticleImaging/MNPDynamics.jl to inspire further research in these directions
Simulations of magnetic particles with arbitrary anisotropies
Alexander Neumann, Thorsten M. Buzug
To simulate the behavior of realistic magnetic particles in magnetic particle imaging it is not enough to perform simulations assuming only a uniaxial magnetic anisotropy energy due to the complex coupling between the magnetic and the mechanic degrees of freedom of the particle in multidimensional excitation fields. Most particles can only be approximated of having uniaxial magnetic anisotropy energy. As such, this work will discuss the shortcoming of currently used models focusing on only uniaxial anisotropy and show how a theoretical model must be defined to allow for arbitrary anisotropy energies. First simulation results showing the differences between different anisotropy energies will be presented at the workshop.
Simultaneous imaging of magnetic nanoparticle concentration, temperature and viscosity with a scanning magnetic particle spectrometer
Jing Zhong, Meinhard Schilling, Frank Ludwig
A new approach of simultaneous imaging of magnetic nanoparticle (MNP) concentration, temperature and viscosity with a custom-built scanning magnetic particle spectrometer (SMPS) is presented. The fundamental f0 and the 3f0 and 5f0 harmonics of the MNPs dominated by Brownian relaxation are measured with the SMPS. The effects of viscosity and temperature on the harmonics are studied in ac magnetic fields with different frequencies and amplitudes. Afterwards, phantom experiments are performed on the MNP samples with different spatial distributions of viscosity and temperature, which demonstrates the feasibility of the proposed approach for simultaneous imaging of MNP concentration, temperature and viscosity imaging.
Keynote 1
The Do's and Don'ts of MPI Scanner Instrumentation
The Do's and Don'ts of MPI Scanner Instrumentation
Lawrence Wald
Lawrence L. Wald, Ph.D., is currently a Professor of Radiology at Harvard Medical School, Affiliated Faculty of the Harvard-MIT Division Health Sciences Technology and Sara & Charles Fabrikant Research Scholar at the Massachusetts General Hospital. He received a BA in Physics at Rice University, and a Ph.D. in Physics from the University of California at Berkeley in 1992 under the direction of Prof. E.L. Hahn with a thesis related to optical detection of NMR. He obtained further (postdoctoral) training in Physics at Berkeley and then in Radiology and MRI at the University of California at San Francisco (UCSF). He began his academic career as an Instructor at the Harvard Medical School and since 1998 has been at the Massachusetts General Hospital Dept. of Radiology A.A. Martinos Center for Biomedical Imaging.His recent work focuses on improving methods for functional brain imaging. He has worked on the benefits and challenges of highly parallel MRI and its application to faster image encoding and parallel excitation and ultra-high field MRI (7 Tesla) methodology, and also improved method for studying the Human Connectome and portable MRI technology. Recent work has included studying the feasibility of functional brain imaging with Magnetic Particle Imaging (MPI) using Cerebral Blood Volume (CBV) contrast and analysis of the instrumentation needed for fMPI of humans. This has also led to extending understanding of Peripheral Nerve Stimulation (PNS) in human MPI and MRI using electromagnetic body models with full nerve atlases and a detailed neuro-dynamic model to predict magneto-stimulation thresholds. Dr. Wald is a Fellow of the International Society of Magnetic Resonance (ISMRM) and the College of Fellows of the American Institute for Medical and Biologial Engineering (AIMBE).
Session 4
Application
Magnetic Particle Imaging for intraoperative margin analysis in breast-conserving surgery
Erica Mason, Eli Mattingly, Konstantin Herb, Sofia Franconi, Monika Sliwiak, Clarissa Cooley, Lawrence Wald
Breast-conserving surgery (BCS) is a commonly utilized treatment for early stage breast cancers but has high reexcision rates due to post-surgery identification of positive margins. A fast, specific, sensitive, easy-to-use tool for assessing margins intraoperatively has been shown to reduce the need for additional surgeries, and while many techniques have been explored, the clinical need is still unmet. We assess Magnetic Particle Imaging (MPI) for intraoperative margin assessment in BCS, using a passively or actively tumor-targeted iron oxide agent and two hardware devices: a hand-held Magnetic Particle (MP) detector for identifying residual tumor in the breast, and a small-bore imager for quickly imaging the tumor distribution in the excised specimen. In this abstract, we present both hardware systems and demonstrate proof-of-concept detection and imaging of clinically-relevant phantoms.
Quasi-simultaneous magnetic particle imaging and navigation of nanomag/synomag-D particles in bifurcation flow experiments
Magnetic Particle Imaging (MPI) is used to visualize the distribution of superparamagnetic nanoparticles within 3D volumes with high sensitivity in real time. Recently, MPI is utilized to navigate micron-sized particles and micron-sized swimmers, since the magnetic field topology of the MPI scanner is well suited to apply magnetic forces. In this work, we analyze the magnetic mobility and imaging performance of nanomag/synomag-D for Magnetic Particle Imaging/Navigation (MPIN). With MPIN the focus fields are constantly switching between imaging and magnetic force mode, thus enabling quasi-simultaneous navigation and imaging of particles. In flow bifurcation experiment with a 100 % stenosis on one branch, we determine the limiting flow velocity of 1.36 mL/s, which allows all particles to flow only through one branch towards the stenosis. During this experiment, we image the accumulation of the particles within the stenosis. In combination with therapeutic substances, this approach has a high potential for targeted drug delivery.
Selective actuation and MPI of magnetic beads
Anna C. Bakenecker, Klaas Bente, Felix Bachmann, Anselm von Gladiss, Damien Faivre, Thorsten M. Buzug
Magnetic beads can serve as drug carries or agents for hyperthermia. For a precise treatment, the magnetic beads need to be steered towards their targeted position. Magnetic objects can be moved by either a magnetic gradient field or by a homogeneous magnetic field with a rotating field vector. Both, a gradient field and a homogeneous field, act on all magnetic objects similarly and therefore a selection between various objects is not possible. Here we show a selective actuation of magnetic beads by superimposing a gradient field with a rotating homogeneous field. With the selection field, forming a field free point, and the focus field with rotating field vector of an MPI scanner, selective actuation is performed. Since tomographic imaging is essential for the real-time tracking of the actuation process, we demonstrate the feasibility to visualize the magnetic beads with MPI before and after actuation.
in vivo dose studies of PEG-coated Magnetic Nanoparticles in Tumor-Associated Macrophages using Magnetic Particle Imaging
Marco Gerosa, Gang Ren, Yanrong Zhang, Patrick Goodwill, Jim Mansfield, Pasquina Marzola, Max Wintermark
Tumor-associated macrophages (TAMs) are thought to be protumoral, enhancing and contributing to cancer progression. The presence of TAMs has been correlated with the metastasis of tumor cells and the inhibition of the antitumoral immune responses mediated by T cells. In this brief paper, we used Magnetic Particle Imaging (MPI) to detect passively targeted TAMs homing to a breast cancer model. TAMs were passively targeted using PEG-coated Magnetic Nanoparticles (PEG-MNPs). Escalating doses of PEG-MNPs were tested to evaluate TAM uptake at different time points. An MPI signal was detected in liver and tumor for all the groups except at the lowest dose. A novel quantitation workflow has also been proposed to calculate the quantity of iron inside the different tissues.
Volumetry in magnetic particle imaging
Julia Wernecke
In this work, we investigate the suitability of MPI as a volumetry tool for the determination of retrograde voiding cystography of the bladder. Measurements were performed in two different experimental coil settings: first with a novel gradiometer providing three orthogonal channels and second a single-channel gradiometer at varying gradient strengths. The volumes were calculated using two different approaches: a calibration approach based on the amount of SPIOs and a threshold approach. We show that with both approaches MPI volumetry is feasible. Finally we present initial in vivo results of a retrograde voiding cystography in rats.
Session 5
Image Reconstruction 2
Reducing displacement artifacts by warping system matrices in efficient joint multi-patch magnetic particle imaging
Marija Boberg, Tobias Knopp, Martin Möddel
The reconstruction of multi-patch magnetic particle imaging data requires a compromise between image quality and calibration time. While optimal image quality is ensured by the joint reconstruction approach, a system matrix needs to be acquired for each patch. One can reuse system matrices by shifting them in space, which decreases the calibration effort but leads to distortions due to field imperfections. In this work, we introduce a method for reducing displacement artifacts in the efficient joint multi-patch reconstruction. Based on the magnetic fields we propose a mapping that warps the central system matrix to capture the spatial displacement of off-center system matrices. In this way, we can maintain the low calibration time while significantly improving the image quality.
Investigation of the spatial resolution and penetration depth of a single-sided MPI device in three-dimensional imaging
Yvonne Blancke Soares, Ksenija Gräfe, Kerstin Lüdtke-Buzug, Thorsten M. Buzug
A one-sided arrangement of the components relevant for magnetic particle imaging leads to improved patient access, as the object size can be unlimited. In this paper, we further investigate the properties of the single-sided MPI system published earlier. A phantom with up to five positions filled with Perimag particles was rotated to evaluate the spatial resolution depending on the orientation of the receive coils. The reconstruction was done with a Kaczmarz algorithm and a Tikhonov regularization with individually calculated regularization parameters for each measurement. The penetration depth and the spatial resolution in the y-,z-plane were evaluated.
Super-resolving reconstruction technique for MPI
Alper Gungor, Can Barış Top
System matrix reconstruction of Magnetic Particle Imaging (MPI) require a time-consuming calibration process. The total number of pixels of the desired image has a direct effect on the calibration time. Although there are various techniques that can shorten the calibration process such as compressive sensing or coded calibration scenes, the increase in total number of pixels still require higher number of samples. In this study, we propose a simple super-resolution technique for MPI images during reconstruction. Using simulations on a field free line MPI scanner system with low drive field amplitude, we show that one can achieve higher resolution images by simply applying super-resolution techniques on the rows of the system matrix. We demonstrate that even simple linear models can help resolve high-resolution structures.
Eigen-reconstructions: a closer look into the System Matrix
Jorge Chacon-Caldera, Heinrich Lehr, Kulthisa Sajjamark, Jochen Franke
Magnetic particle imaging (MPI) offers an exceptional set of advantages including high sampling efficiency and sub-millimeter spatial resolution. The former is maximized using ad-hoc sampling trajectories; the latter relies on the compensation of the point spread function of the superparamagnetic iron oxide particles (SPIOs) necessary for the MPI signal. The System Matrix (SM) approach for reconstruction uses a pre-calibration measurement and achieves both purposes simultaneously, relating the concentration of SPIOs and the particle response to the signal. Consequently, the SM’s quality will largely influence the reconstruction. Considering the multitude of factors involved in the reconstruction, it is difficult to identify sources of image artifacts. In this work, we demonstrate the potential to use reconstructions of individual measurements within the SM (eigen-reconstruction) as a test for both SM and reconstruction quality. We also present an algorithm to enhance image quality using eigen-reconstructions.
Session 6
Application
Estimating orientation using multi-contrast MPI
Martin Möddel, Florian Griese, Tobias Kluth, Tobias Knopp
Magnetic particle imaging (MPI) is a tracer based tomographic imaging technique that uses static and oscillating magnetic fields to generate an image contrast from the spatial distribution of magnetic nanoparticles. Recent investigations have shown that the MPI is able to generate additional contrasts from different tracer materials or their environments. For example, multi-contrast MPI can be used to determine the viscosity or temperature of the particle environment, or to distinguish tracer particles based on their core size. In this work, we investigate a novel contrast based on the magnetic anisotropy of immobilized particles which allows to estimate the orientation of samples.
Temperature Mapping via Relaxation-Based Color MPI
Mustafa Utkur, Emine Ulku Saritas
In magnetic particle imaging (MPI), the relaxation behavior of the nanoparticles has been exploited to expand quantitative mapping capabilities of MPI to applications such as viscosity mapping and temperature mapping. We have previously proposed a technique called TAURUS to estimate the relaxation time constant directly from the MPI signal, and demonstrated its viscosity mapping capabilities via imaging experiments. In this work, we extend TAURUS to demonstrate its temperature mapping capability via 1D imaging experiments at two different temperatures.
Blind Source Separation for Multi-Color MPI
Semih Kurt, Yavuz Muslu, Emine Ulku Saritas
In magnetic particle imaging (MPI), different magnetic nanoparticles (MNPs) in the same field-of-view can be distinguished via color-MPI techniques. Existing system-function-based techniques require extensive calibration scans, whereas x-space-based approaches require either multiple scans at different drive field parameters, or rely on the underlying mirror symmetry of the adiabatic MPI signal. In this work, we propose a novel blind source separation technique for multi-color MPI, exploiting the distinct signal delays of different MNPs. The proposed technique blindly decomposes the MPI signals from different MNPs, which can then be individually reconstructed and assigned to separate color channels to form a multi-color MPI image.
MPI based intracranial pressure (ICP) monitor for hydrocephalus patients
Mert Şener, Barış Oğuz Gürses, Özge Akbülbül, Aysun Baltacı
Intraventricular shunts are the conventional medical devices for the treatment of hydrocephalus. The most common and life treating complication of the implantation of these devices is the probability of the blockage or the misalignment of shunts after the surgery. The most command way to diagnose these complications is the application of Computed Tomography. Unfortunately, frequent exposure to x-ray radiation can have degrading effects in the heath of these patients and even, it can lead to the cancer. Magnetic Particle Imaging is a tracer based imaging modality and has no adverse effects on health as x-ray based methods. In this study, an elastic capsule filled with super paramagnetic iron oxide nanoparticles is used for the measurement of the intracranial pressure. The diameter of capsule is measured by the magnetic particle imaging method.
Session 7
Application + Patient Safety
Tailoring magnetic supraparticles for object identification by magnetic particle spectroscopy
Stephan Müssig, Florian Fidler, Daniel Haddad, Karl-Heinz Hiller, Susanne Wintzheimer, Karl Mandel
Marking and identification of materials is becoming increasingly important due to complex global resource and supply chains. In this work, a miniaturized magnetic marking technology based on so-called supraparticles is presented. The hierarchical buildup of these microparticles, which are assembled from nanoparticles, allows to precisely tailor their structure. Superparamagnetic iron oxide nanoparticles as building blocks are used in this work. By surface modification and mixing them with silica nanoparticles, respectively, the supraparticle structure is varied. It is demonstrated that these structural modifications are readily detected by magnetic particle spectroscopy (MPS). Thereby, various distinguishable magnetic signals are feasible, which are even detected after incorporation into dark plastic. The presented magnetic marking technology thus proves its potential as an alternative marking technology to optical labels.
Magnetic Particle Fingerprinting using Arbitrary Waveform Relaxometer
Ecrin Yagiz, Mustafa Utkur, Can Barış Top, Emine Ulku Saritas
In magnetic particle imaging (MPI), the information about the local environment, such as its viscosity and temperature, can be inferred via the relaxation behavior of the nanoparticles. As the nanoparticle signal also changes with drive field (DF) parameters, one potential problem for quantitative mapping applications is the optimization of these parameters. In this work, an accelerated framework is proposed for characterizing the unique response of a nanoparticle under different environmental settings. The proposed technique, called magnetic particle fingerprinting (MPF), rapidly sweeps a wide range of DF parameters, mapping the unique tau-fingerprint of a sample. This technique can enable simultaneous mapping of several parameters (e.g., viscosity, temperature, nanoparticle type, etc.) with reduced scan time.
Stent Lumen Quantification of 21 Endovascular Stents with MPI
Franz Wegner, Anselm von Gladiss, Julian Haegele, Ulrike Grzyska, Malte Sieren, Kerstin Lüdtke-Buzug, Jörg Barkhausen, Thorsten Buzug, Thomas Friedrich
Restenoses are a common problem after stent implantations and may cause new ischemic events, e.g. heart attacks and strokes. Thus, early diagnosis and treatment of in stent stenoses has tremendous clinical impact. Visualization and quantification of the stent lumen with the established noninvasive imaging modalities MRI and CT is severely limited by stent induced artifacts. The aim of this study was to investigate whether MPI can quantify the stent lumen accurately.
Safety of a new stent design during Magnetic Particle Imaging
Ulrike Grzyska, Thomas Friedrich, Julian Haegele, Thorsten M Buzug, Joerg Barkhausen, Franz Wegner
Aortic coarctation is a potentially life-threatening disease in newborns that requires early treatment. Recently, a new stent was developed for this purpose, which can be redilatated and thus adapted to the growth of the infant’s aorta. Due to the lack of ionizing radiation MPI is a very promising imaging technique for this clinically very important application in children. Therefore, the safety of this stent with regard to heating by oscillating magnetic fields must be investigated before the stent can be used.
MPI visualization and inductive heating of hybrid implant fibers
Benedikt Mues, Brice Tiret, Benedict Bauer, Jeanette Ortega, Thomas Gries, Thomas Schmitz-Rode, Patrick Goodwill, Ioana Slabu
In this study, we evaluate the hyperthermia efficiency of polypropylene (PP) fibers with incorporated magnetic nanoparticles (MNP), which are used to develop inductive heatable stents in cancer therapy. Further, we investigate their depiction in magnetic particle imaging (MPI). We show that the intrinsic loss power (ILP) value depends on the MNP agglomeration state and their concentration inside the fibers, while the intensity values in the MPI images show a linear response with MNP concentration. We conclude that MNP dynamic magnetic behavior strongly changes with different MNP agglomeration states and magnetic field settings.
Functional MPI (fMPI) of hypercapnia in rodent brain with MPI time-series imaging
Konstantin Herb, Erica E. Mason, Eli Mattingly, Joseph B. Mandeville, Emiri T. Mandeville, Clarissa Zimmerman Cooley, Lawrence L. Wald
MPI has been proposed as an alternative to fMRI for detecting cerebral blood volume (CBV) changes associated with brain activation due to potentially higher sensitivity, possibly enabling single-patient studies. In this work, we show preliminary neuroimaging data of CBV modulation with hypercapnia acquired in vivo on a rodent MPI scanner designed for time-series imaging. This continuously rotating 2D projection field free line imager enables time-series imaging with temporal resolution of up to 3 seconds. As a first demonstration of “fMPI”, we acquire time-series images of a rodent brain with 5 second temporal resolution with the animal undergoing alternating 3-minute periods of either hyper- or hypocapnia. Image intensity changes from CBV modulation of the injected SPIONs concentration were detected with a CNR of up to 14 in brain pixels.
Keynote 2
Magnetic Particle Imaging – one fascinating pillar of Bruker’s multimodal life science portfolio
Magnetic Particle Imaging – one fascinating pillar of Bruker’s multimodal life science portfolio
Jochen Franke
Preclinical imaging plays an important role in the understanding of biological processes in both healthy and diseased states and of responses to pharmacological, physiological or environmental challenges. Especially in demanding times like the current COVID-19 pandemic, a comprehensive understanding of biological systems is crucial. The use of state-of-the-art analytical technologies can significantly advance clinical diagnosis and therapy routines.
Session 8
Instrumentation 2
OS-MPI: an open-source magnetic particle imaging project
Eli Mattingly, Erica Mason, Konstantin Herb, Monika Śliwiak, Katrin Brandt, Clarissa Cooley, Lawrence Wald
Bruker BioSpin is a renowned provider of state-of-the-art imaging technologies, ranging from Magnetic Resonance Imaging (MRI), Computed Tomography (CT), Positron Emission Tomography (PET), Single Photon Emission Computed Tomography (SPECT) to its youngest imaging technology, Magnetic Particle Imaging (MPI). With our mission to develop each imaging technology to its best, Bruker drives innovation in new methodologies and solutions for scientists enabling ground-braking discoveries. Our instruments allow for important assessments of healthy and diseased mechanisms at organ, tissue, cell, and molecular levels. Preclinical imaging is also central to evaluate the effectiveness and safety of new treatments and describing drug distribution patterns before clinical usage. That is why Bruker continues to invest in innovation and new technologies, especially in the current demanding times to support the fight against the COVID-19 pandemic.
Organ specific mouse head coil for improved image quality in magnetic particle imaging
Matthias Gräser, Tom Liebing, Patryk Szwargulski, Fynn Förger, Florian Thieben, Peter Ludewig, Tobias Knopp
Implementation of a Gradiometer Receive Coil for a Single-Sided FFL MPI Scanner
Jason Pagan, Juehao Lin, Alexey A Tonyushkin
For head-to-toe investigations in your research, we seamlessly combine different imaging technologies in multimodal, easy-to-use instruments. Best-in-class hardware and software packages offer optimized workflows from animal handling to morphological and functional data acquisition to image reconstruction and post-processing steps. This includes quantification and visualization tools for various biomedical imaging applications.
Design of a Doubly Tunable Gradiometer Coil
Ahmet Rahmetullah Çağıl, Bilal Tasdelen, Emine Ulku Saritas
Evaluation of spatio-temporal resolution of MPI scanners with a dynamic bolus phantom
Silvio Dutz, Anton Stang, Lucas Wöckel, Olaf Kosch, Patrick Vogel, Cordula Grüttner, Volker C. Behr, Frank Wiekhorst
With the help of numerous collaborations with leading research centers and our dynamic development teams, Bruker is investing in the advancement of Magnetic Particle Imaging in the preclinical area, paving the translational way to clinical perspectives. The use of nanomaterials and their specific response to external magnetic fields is not only crucial for molecular imaging, but opens the door to the development of novel theranostic strategies, which in turn can improve patient outcomes and save lives.
HYPER localized hyperthermia – early results
Matthias Weber, Daniel Hensley, Blayne Kettlewell, Andrew Mark, Ryan Orendorff, Maximilian Peters, Brice Tiret, Elaine Yu, Patrick Goodwill
A heating coil insert for a preclinical MPI scanner
Huimin Wei, Andre Behrends, Thomas Friedrich, Thorsten Buzug
Be inspired by the recent achievements of our outstanding MPI community in the life sciences and join us to take molecular imaging to the next level.
