Magnetic Particle Spectroscopy Papers

Stem Cell Vitality Assessment Using
Magnetic Particle Spectroscopy

Florian Fidler1, Maria Steinke2, Alexander Kraupner3, Cordula Grüttner4, Karl-Heinz Hiller1, Andreas Briel3, Fritz Westphal4, Heike Walles2, and Peter Michael Jakob1

1 Research Center Magnetic-Resonance-Bavaria, Würzburg 97074, Germany
2 Fraunhofer Project Group Regenerative Technologies in Oncology, Tissue Engineering and Regenerative Medicine, Würzburg 97070, Germany
3 nanoPET Pharma GmbH, Berlin 10115, Germany
4 Micromod GmbH, Rostock-Warnemünde 18119, Germany
IEEE TRANSACTIONS ON MAGNETICS, VOL. 51, NO. 2, FEBRUARY 2015

In the field of regenerative medicine, we focus on repairing damaged tissue using appropriate cells for therapy that have healing capacities, such as human mesenchymal stem cells (hMSCs). Tissue healing using stem cells will only be possible if the cells can be homed to their target. Beside cell homing at the targeted organ, assessing the cell vitality is of paramount interest during the healing process. To guarantee cell homing, hMSCs have to be labeled for long-term, noninvasive cell monitoring. Cell homing of labeled cells with iron oxide nanoparticles can be tracked with various methods like magnetic particle imaging or magnetic resonance imaging.

In this paper, we present our first results in monitoring the cell vitality in vitro based on magnetic particle spectroscopy findings.

Magnetic Particle Spectrometry of Fe3O4 Multi-Granule Nanoclusters

Lijun Pan1, Bum Chul Park1, Micheal Ledwig2, Leon Abelmann3, 4, and Young Keun Kim1

1 Department of Materials Science and Engineering, Korea University, Seoul 02481, South Korea
2 Pure Devices, Würzburg 97084, Germany
3 KIST Europe, Saarbrücken 66123, Germany
4 University of Twente, Enschede 7522, The Netherlands
IEEE TRANSACTIONS ON MAGNETICS, VOL. 53, NO. 11, NOVEMBER 2017

Magnetic particle imaging (MPI) is a novel high-resolution medical imaging method that does not use ionizing radiation, but safe iron oxide nanoparticles as contrast agents. By employing magnetite (Fe3O4) multi-granule nanoclusters (MGNCs), one has two control parameters: the diameter of the particles and that of granules in single particles. Here we investigate the effect of the size of the particles at constant granule size, as well as the effect of granule size at constant particle size on the magnetization reversal.

The saturation magnetization Ms value increases with increasing granule diameter and particle diameter, while the coercivity Hc value reaches a maximum at a particle size of about 60 nm. MGNCs with an average particle size of 77 nm and granule diameter of 17 nm show a larger response in the higher harmonics compared to the commercial reference, FeraSpin R dispersion, at both 20 and 30 mT. This result demonstrates that the MGNC concept allows tailoring of the magnetic properties of the particles to the imaging conditions in MPI. 

Anisotropic Magnetic Supraparticles with a Magnetic Particle Spectroscopy Fingerprint as Indicators for Cold-Chain Breach

Stephan Müssig, Tim Granath, Tim Schembri, Florian Fidler,Daniel Haddad, Karl-Heinz Hiller,Susanne Wintzheimer, and Karl Mandel*,,§

†Chemical Technology of Materials Synthesis, University of Wuerzburg, Roentgenring 11, 97070 Würzburg, Germany
‡Magnetic Resonance and X-ray Imaging Department, Development Center X-ray Technology EZRT, Fraunhofer Institute for Integrated Circuits IIS, Am Hubland, 97074 Würzburg, Germany
§Fraunhofer Institute for Silicate Research ISC, Neunerplatz 2, 97082 Würzburg, Germany
UNIV LIBRARY OF WUERZBURG on July 31, 2019

Magnetic particle spectroscopy (MPS) is used in this work to obtain a magnetic fingerprint signal from anisotropic supraparticles, i.e., micro-rods assembled from superparamagnetic iron oxide nanoparticles. Exceeding its intended purpose of nanoparticle characterization for biomedical magnetic particle imaging, it is shown that MPS is capable of resolving structural differences between the anisotropic alignment of individual nanoparticles and its isotropic counterpart. Additionally, orientation-dependent MPS signal variations of anisotropic supraparticles are identifiable. This finding enables the detection of cold-chain breaches (for instance, during delivery of a product that needs to be cooled all of the time) by recording the initial and final MPS signals of micro-rod samples integrated into the container of a frozen product.

Supraparticles with a Magnetic Fingerprint Readable by Magnetic Particle Spectroscopy: An Alternative beyond Optical Tracers

Stephan Müssig, Florian Fidler, Daniel Haddad, Karl-Heinz Hiller, Susanne Wintzheimer, and Karl Mandel*

S. Müssig, Dr. S. Wintzheimer, Dr. K. Mandel
Chemical Technology of Materials Synthesis
University of Würzburg, Röntgenring 11
97070 Würzburg, Germany. 2019.

Marking and identification of materials is becoming increasingly important due to complex global resource and supply chains. Luminescent particle-based markers have come to the forefront due to their small dimensions and their ability to be integrated in diverse materials. However, light-absorbing materials can hardly be marked by these particles, thus leading to insufficient recycling rates of, e.g., black plastics. In this work, microparticles with a unique magnetic fingerprint are tailored by modification of their nanoparticle building blocks. This fingerprint tailoring is achieved either by combination of magnetic building blocks with nonmagnetic ones in the supraparticles or, alternatively, by surface modification of the building blocks. An easy-to-use device, based on the principle of magnetic particle spectroscopy (MPS), is established to resolve the magnetic fingerprint information. This facilitates the employment of magnetic supraparticles as markers for product tracking and identification. As a proof of concept, it is shown that such particals enable the marking of black plastic.

Research Lab MRI Papers

High resolution ex-vivo imaging of a rodent kidney with a portable MR-Scanner at 0.5 Tesla: Initial results in relation to state
of the art techniques

Florian Lietzmann1, Christina Hopfgarten1, Jorge Chacón-Caldera1, Stefania Geraci2, and Lothar R. Schad1

1Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany, 2Medical Research Center, Heidelberg University, Mannheim, Germany

Filtration processes in the kidney are fundamental for the clearance of waste products from the metabolism. A renal impairment can quickly lead to a malfunctioning blood pressure and adrenal hormone regulation or even uremia with the eventual need of dialysis or transplantation. The European cooperation Eurotransplant, including eight countries, counted 3299 performed kidney transplants in the year 2011 [1]. Looking at any waiting list for kidney transplantation, the need for an early diagnosis to avoid transplantations becomes obvious. Therefore, alternative diagnostic modalities that allow to the detection of even slight morphological or anatomical renal changes gain further importance. To improve the understanding of the relevant processes in the kidney it is important to have a thorough knowledge of the kidney’s basic composition, making high-resolution MR imaging indispensable. Nowadays high-resolution images are acquired either with high-field animal scanners or a special coil setup for human whole body systems. Hence, renal imaging using MRI is crucial but not available to many institutions because until now it relied in highend systems working at high or ultra high field strengths. As an alternative, a low-field portable MR-system which can achieve similar resolutions like a small animal system can provide such images. This work is presents initial results of the acquisition with the portable system at 0.5 T in relation to state of the art methods.

Tabletop magnetic resonance elastography for the measurement
of viscoelastic parameters of small tissue samples

Selcan Ipek-Ugay a, Toni Drießle b, Michael Ledwig b, Jing Guo a, Sebastian Hirscha, Ingolf Sack a, Jürgen Braun c,

a Department of Radiology, Charité – Universitätsmedizin Berlin, Berlin, Germany
b Pure Devices GmbH, Würzburg, Germany
c Institute of Medical Informatics, Charité – Universitätsmedizin Berlin, Berlin, Germany.  2014 Elsevier Inc. All rights reserved.

We demonstrate the feasibility of low-cost tabletop MR elastography (MRE) for quantifying the complex shear modulus G⁄ of small soft biological tissue samples as provided by pathologists. The MRE system was developed based on a tabletop MRI scanner equipped with a 0.5 T permanent magnet and a tissue sample holder mounted to a loudspeaker. A spin echo sequence was enhanced with motion-encoding gradients of 250 mT/m amplitude synchronized to acoustic vibration frequencies. Shear wave images suitable for elastography were acquired between vibration frequencies of 0.5 and 1 kHz in agarose, ultrasound gel, porcine liver, porcine skeletal muscle, and bovine heart with a spatial resolution of 234 lm pixel edge length. The measured frequency dependence of G⁄ agreed well with previous work based on high-field MR systems. The ratio between loss and storage moduli was highest in liver and ultrasound gel, followed by muscle tissue and agarose gel while ultrasound gel and liver showed similarly low storage moduli compared to the other samples. The shear wave to noise ratio is an important imaging criteria for MRE and was about 4.2 times lower for the preliminary setup of the 0.5 T tabletop system compared to a 7 T animal scanner. In the future, the new tabletop MRE system may serve as a low cost device for preclinical research on the correlation of viscoelastic parameters with histopathology of biological samples.

Passive artifact behavior prediction of interventional tools in high-field MRI using a 0.55T portable benchtop MR scanner

H. Abadi 1, J. Krug1, A. Illanes1, M. Friebe1

1Faculty of Electrical Engineering and Information Technology, Chair for Intelligente Katheter, Otto-von-Guericke University, Magdeburg, Germany

Using magnetic resonance imaging (MRI) for guiding minimally invasive interventions requires surgical devices which on one hand are visible in the MR image but on the other hand do not generate large artifacts, which distort the overall imaging process. Passive markers are one way to visualize devices such as catheters or biopsy needles in MRI. The evaluation of newly developed passive markers usually requires access to high-field MRI scanners (1:5 T and 3 T). This makes the practical evaluation time-consuming and expensive.Hence, we propose to use a high-resolution, low field (0:55 T)benchtop MRI system to quantify the size of an artifact and to make a prediction for its corresponding size in a clínicas high-field system. For the evaluation of the proposed method, catheters coated with different passive marker materials in varying concentrations were imaged in the 0:55 T benchtop MRI scanner as well as in clinical 3 T MRI system using FLASH sequences. The experimental results revealed that an artifact prediction based on measurements in the 0:55 T is possible for the tested marker materials. Hence, the proposed approach has a high potential for testing newly developed medical devices at a low cost, in less time and during the development process for fast feedback.

Tabletop MR Elastography (MRE): Preliminary Results Towards an Assessment of Frozen Tissue Bank Samples

Reiter R, GuidettiM, ZampiniMA, MajumdarS, PalnitkarH, Royston T, Klatt D

The University of Illinois at Chicago

Purpose: 

Tabletop MRE is a low-cost method for assessing mechanical properties of small tissue specimens1,2. 

Frozen tissue banks potentially facilitate access to large amounts of well-preserved specimens3. 

However, evidence about changes of rheological tissue properties through freeze-thaw events is currently limited. 

Aim: To characterize changes of fresh ex vivo (native), and frozen and thawed     (lysed) specimens of porcine muscle, liver and kidney tissue. 

1. Braun J et al. MagnResonMed 2017

2. Ipek-UgayS et al. J MagnReson2015 

3. ShabihkhaniM et al. Clin Biochem2014

//]]>