A built-in coil system attached to the inside walls of a magnetically shielded room for generating an ultra-high magnetic field homogeneity.

The homogeneity of the magnetic field generated by a coil inside a magnetic shield is essential for many applications, such as ultra-low field nuclear magnetic resonance or spin precession experiments. In the course of upgrading the Berlin Magnetically Shielded Room (BMSR-2) with a new inserted Permalloy layer of side length 2.87 m, we designed a built-in coil consisting of four identical square windings attached to its inside walls.

Noninvasive monitoring of blood flow using a single magnetic microsphere.

Noninvasive medical imaging of blood flow relies on mapping the transit of a contrast medium bolus injected intravenously. This has the draw-back that the front of the bolus widens until the tissue of interest is reached and quantitative flow parameters are not easy to obtain. Here, we introduce high resolution (millimeter/millisecond) 3D magnetic tracking of a single microsphere locally probing the flow while passing through a vessel.

Improved sensitivity and limit-of-detection using a receive-only coil in magnetic particle imaging.

Magnetic particle imaging (MPI) is an imaging modality capable of quantitatively determining the 3D distribution of a magnetic nanoparticle (MNP) ensemble. In this work, we present a method for reducing the MNP limit of detection by employing a new receive-only coil (Rx-coil) for signal acquisition. The new signal detector is designed to improve the sensitivity and thus quality of reconstructed images.

Novel magnetic multicore nanoparticles designed for MPI and other biomedical applications: From synthesis to first in vivo studies.

Synthesis of novel magnetic multicore particles (MCP) in the nano range, involves alkaline precipitation of iron(II) chloride in the presence of atmospheric oxygen. This step yields green rust, which is oxidized to obtain magnetic nanoparticles, which probably consist of a magnetite/maghemite mixed-phase. Final growth and annealing at 90°C in the presence of a large excess of carboxymethyl dextran gives MCP very promising magnetic properties for magnetic particle imaging (MPI), an emerging medical imaging modality, and magnetic resonance imaging (MRI).

Selection of potential iron oxide nanoparticles for breast cancer treatment based on in vitro cytotoxicity and cellular uptake.

Superparamagnetic iron oxide nanoparticles (SPIONs) are promising tools for the treatment of different diseases. Their magnetic properties enable therapies involving magnetic drug targeting (MDT), hyperthermia or imaging. Depending on the intended treatment, specific characteristics of SPIONs are required.

Magnetic field imaging with microfabricated optically-pumped magnetometers.

A multichannel imaging system is presented, consisting of 25 microfabricated optically-pumped magnetometers. The sensor probes have a footprint of less than 1 cm and a sensitive volume of 1.5 mm × 1.

Magnetic Particle Spectroscopy Reveals Dynamic Changes in the Magnetic Behavior of Very Small Superparamagnetic Iron Oxide Nanoparticles During Cellular Uptake and Enables Determination of Cell-Labeling Efficacy.

In vivo tracking of nanoparticle-labeled cells by magnetic resonance imaging (MRI) crucially depends on accurate determination of cell-labeling efficacy prior to transplantation. Here, we analyzed the feasibility and accuracy of magnetic particle spectroscopy (MPS) for estimation of cell-labeling efficacy in living THP-1 cells incubated with very small superparamagnetic iron oxide nanoparticles (VSOP). Cell viability and proliferation capacity were not affected by the MPS measurement procedure.

Magnetorelaxometry procedures for quantitative imaging and characterization of magnetic nanoparticles in biomedical applications.

Background: Quantitative knowledge about the spatial distribution and local environment of magnetic nanoparticles (MNPs) inside an organism is essential for guidance and improvement of biomedical applications such as magnetic hyperthermia and magnetic drug targeting. Magnetorelaxometry (MRX) provides such quantitative information by detecting the magnetic response of MNPs following a fast change in the applied magnetic field.

Methods: In this article, we review our MRX based procedures that enable both the characterization and the quantitative imaging of MNPs in a biomedical environment.

The 170ms Response to Faces as Measured by MEG (M170) Is Consistently Altered in Congenital Prosopagnosia.

Modularity of face processing is still a controversial issue. Congenital prosopagnosia (cPA), a selective and lifelong impairment in familiar face recognition without evidence of an acquired cerebral lesion, offers a unique opportunity to support this fundamental hypothesis. However, in spite of the pronounced behavioural impairment, identification of a functionally relevant neural alteration in congenital prosopagnosia by electrophysiogical methods has not been achieved so far.

Flow cytometry for intracellular SPION quantification: specificity and sensitivity in comparison with spectroscopic methods.

Due to their special physicochemical properties, iron nanoparticles offer new promising possibilities for biomedical applications. For bench to bedside translation of super-paramagnetic iron oxide nanoparticles (SPIONs), safety issues have to be comprehensively clarified. To understand concentration-dependent nanoparticle-mediated toxicity, the exact quantification of intracellular SPIONs by reliable methods is of great importance.

Fetal magnetocardiography measurements with an array of microfabricated optically pumped magnetometers.

Following the rapid progress in the development of optically pumped magnetometer (OPM) technology for the measurement of magnetic fields in the femtotesla range, a successful assembly of individual sensors into an array of nearly identical sensors is within reach. Here, 25 microfabricated OPMs with footprints of 1 cm(3) were assembled into a conformal array. The individual sensors were inserted into three flexible belt-shaped holders and connected to their respective light sources and electronics, which reside outside a magnetically shielded room, through long optical and electrical cables.

Magnetoencephalographic accuracy profiles for the detection of auditory pathway sources.

The detection limits for cortical and brain stem sources associated with the auditory pathway are examined in order to analyse brain responses at the limits of the audible frequency range. The results obtained from this study are also relevant to other issues of auditory brain research. A complementary approach consisting of recordings of magnetoencephalographic (MEG) data and simulations of magnetic field distributions is presented in this work.

Characterization of magnetic nanoparticle systems with respect to their magnetic particle imaging performance.

The optimization of magnetic nanoparticles (MNPs) as markers for magnetic particle imaging (MPI) requires an understanding of the relationship between the harmonics spectrum and the structural and magnetic properties of the MNPs. Although magnetic particle spectroscopy (MPS) - carried out at the same excitation frequency as the given MPI system - represents a straightforward technique to study MNPs for their suitability for MPI, a complete understanding of the mechanisms and differences between different tracer materials requires additional measurements of the static and dynamic magnetic behavior covering additional field and time ranges. Furthermore, theoretical models are needed, which correctly account for the static and dynamic magnetic properties of the markers.

Efficient drug-delivery using magnetic nanoparticles--biodistribution and therapeutic effects in tumour bearing rabbits.

Unlabelled: To treat tumours efficiently and spare normal tissues, targeted drug delivery is a promising alternative to conventional, systemic administered chemotherapy. Drug-carrying magnetic nanoparticles can be concentrated in tumours by external magnetic fields, preventing the nanomaterial from being cleared by metabolic burden before reaching the tumour. Therefore in Magnetic Drug Targeting (MDT) the favoured mode of application is believed to be intra-arterial.

Validity of subthalamic-cortical coherency observed in patients with Parkinson's disease.

Simultaneous magnetoencephalography (MEG) and local field potential (LFP) recordings in patients with Parkinson's disease (PD) undergoing deep brain stimulation (DBS) treatment is a promising tool for both clinical application and basic research. Recordings can be accomplished during the time interval between electrode insertion and its connection to the pulse generator while electrodes are being externalized. In nine PD patients, coherence (COH) between LFP and MEG signals was calculated from the data of a 5-min simultaneous MEG-LFP rest recording.

Certain types of iron oxide nanoparticles are not suited to passively target inflammatory cells that infiltrate the brain in response to stroke.

Intravenous administration of iron oxide nanoparticles during the acute stage of experimental stroke can produce signal intensity changes in the ischemic region. This has been attributed, albeit controversially, to the infiltration of iron-laden blood-borne macrophages. The properties of nanoparticles that render them most suitable for phagocytosis is a matter of debate, as is the most relevant timepoint for administration.

Adapting source grid parameters to improve the condition of the magnetostatic linear inverse problem of estimating nanoparticle distributions.

The problem of estimating magnetic nanoparticle distributions from magnetorelaxometric measurements is addressed here. The objective of this work was to identify source grid parameters that provide a good condition for the related linear inverse problem. The parameters investigated here were the number of sources, the extension of the source grid, and the source direction.

Magnetic resonance imaging at frequencies below 1 kHz.

Within the magnetic resonance imaging (MRI) community the trend is going to higher and higher magnetic fields, ranging from 1.5 T to 7 T, corresponding to Larmor frequencies of 63.8-298 MHz.

Magnetized aerosols comprising superparamagnetic iron oxide nanoparticles improve targeted drug and gene delivery to the lung.

Purpose: Targeted delivery of aerosols could not only improve efficacy of inhaled drugs but also reduce side effects resulting from their accumulation in healthy tissue. Here we investigated the impact of magnetized aerosols on model drug accumulation and transgene expression in magnetically targeted lung regions of unanesthetized mice.

Methods: Solutions containing superparamagnetic iron oxide nanoparticles (SPIONs) and model drugs (fluorescein or complexed plasmid DNA) were nebulized to unanesthetized mice under the influence of an external magnetic gradient directed to the lungs.

Identification of magnetic nanoparticles for combined positioning and lentiviral transduction of endothelial cells.

Purpose: The combination of magnetic nanoparticles (MNPs) with a magnetic field is a powerful approach to enable cell positioning and/or local gene therapy. Because physical requirements for MNPs differ between these two applications we have explored whether the use of different MNPs can provide site-specific positioning combined with efficient viral transduction of endothelial cells (ECs).

Methods: A variety of MNPs was screened for magnetic cell labeling and lentivirus binding.

Magnetorelaxometry assisting biomedical applications of magnetic nanoparticles.

Due to their biocompatibility and small size, iron oxide magnetic nanoparticles (MNP) can be guided to virtually every biological environment. MNP are susceptible to external magnetic fields and can thus be used for transport of drugs and genes, for heat generation in magnetic hyperthermia or for contrast enhancement in magnetic resonance imaging of biological tissue. At the same time, their magnetic properties allow one to develop sensitive and specific measurement methods to non-invasively detect MNP, to quantify MNP distribution in tissue and to determine their binding state.

Minimal-invasive magnetic heating of tumors does not alter intra-tumoral nanoparticle accumulation, allowing for repeated therapy sessions: an in vivo study in mice.

Localized magnetic heating treatments (hyperthermia, thermal ablation) using superparamagnetic iron oxide nanoparticles (MNPs) continue to be an active area of cancer research. For generating the appropriate heat to sufficiently target cell destruction, adequate MNP concentrations need to be accumulated into tumors. Furthermore, the knowledge of MNP bio-distribution after application and additionally after heating is significant, firstly because of the possibility of repeated heating treatments if MNPs remain at the target region and secondly to study potential adverse effects dealing with MNP dilution from the target region over time.

Are brain currents detectable by means of low-field NMR? A phantom study.

A number of different methods have been developed in order to detect the spreading of neuronal currents by means of noninvasive imaging techniques. However, all of these are subjected to limitations in the temporal or spatial resolution. A new approach of neuronal current detection is based on the use of low-field nuclear magnetic resonance (LF-NMR) that records brain activity directly.