International Journal on Magnetic Particle Imaging (IJMPI)
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iMPI-guided angiography in a human cadaveric perfusion model
No full textThis study investigates the use of a portable, human-sized Magnetic Particle Imaging (MPI) scanner in a human cadaveric perfusion model for real-time vascular imaging. Combined with X-ray Digital Subtraction Angiography (DSA), MPI demonstrated high temporal resolution, enabling continuous monitoring of blood flow. MPI\u27s radiation-free nature offers advantages for certain clinical applications, positioning it as a promising tool for interventional radiolog
Microscopy study of magnetic fluid hyperthermia on breast cancer cells
No full textMagnetic fluid hyperthermia (MFH) using magnetic nanoparticles that produce heat in response to an external alternating magnetic field is a promising therapy in cancer treatment offering the possibility to deliver targeted treatment, focusing the energy source to achieve doses that are selectively localized within the tumor volume. In this work, we systematically study MFH treatment at various alternating magnetic field (AMF) frequencies and iron oxide nanoparticles (30 nm) concentrations on breast cancer cells in vitro using optical microscopy. Calorimetry measurements show that therapeutic temperature range in the ferrofluid is reached after about 30 s at 402 kHz and 300 G. Microscopy results reveal that at sufficient ferrofluid concentrations > 25 ?L, cancer cell death is caused by the AMF treatment at 300 G and 402 kHz for 30 min. Further experimental development towards in situ temperature and microscopy monitoring is planned
Capturing Magnetic Nanoparticles with Different Permanent Magnet Shapes in a Microchannel System
No full textThis study examines the influence of different permanent magnet geometries (cube, ring, disc, and Halbach array) on capturing magnetic fluorescent nanoparticles (Synomag,70m) for magnetic drug delivery. Magnetic flux density mapping was performed with a custom setup using a 3MTS Teslameter, ensuring precise magnetization profiling around each magnet. A calibration curve for fluorescence intensity developed through regression analysis of Synomag nanoparticle concentrations, enhanced imaging accuracy. Python line profiling revealed that the Halbach array achieved the highest capture efficiency, reaching a concentration of 10 mg/ml, compared to 5.7 mg/ml for the cubic, 4 mg/ml for the disc, and 2 mg/ml for the ring magnet, under a flow velocity of 10 mm/s. Our results highlight the critical role of magnet design in magnetic nanoparticle capture and distribution, with the Halbach array excelling in high-concentration applications and cubic/disc magnets favoring even distribution. The Halbach array likely excels because it creates a high magnetic field strength and a steep gradient (?B) in the region near its surface. This combination ensures efficient particle capture by balancing the drag forces from the fluid flow with a localized, focused magnetic force, making it highly effective in the given flow configuration.
Toward a Non-Mechanical 3D MPI System for Combining Imaging and Brain Stimulation
No full textTo probe and understand neurobiological systems, neuroscientists require minimally invasive, high resolution tools for targeted modulation of the brains of rodent models. One emerging technique for "magnetothermal" stimulation involves introducing magnetic nanomaterials into targeted regions of the brain and using radiofrequency alternating magnetic fields to produce localized thermal gradients that trigger nearby temperature-sensitive ion channels. Magnetic particle imaging (MPI) similarly makes use of radiofrequency magnetic fields to drive a non-linear magnetization response of magnetic nanoparticle tracers, suggesting the possibility for a combined system. Such a device could enable real-time monitoring of the spatial distribution of magnetic material and potentially also target the delivery of heat to different brain regions. One major challenge to merging these technologies in a single device is that magnetothermal stimulation requires a higher operating frequency (150kHz) than typical MPI (10s of kHz) and a high amplitude of approximately 40 mT, while also ideally demanding a resolution on the order of microns. This poster describes initial progress toward a non-mechanical 3D MPI system operating at these conditions within a ~2.5 cm³ volume using four Maxwell coil pairs. A steel yolk designed as a “closed-flux-loop” system enhances magnetic field density, enabling a small field-free point with the goal off sub-millimeter localized stimulation. This system aims to offer a precise, flexible tool for non-invasive neurobiological studies, advancing neuromodulatory technique development
Initial MRI Results Using Open-Sided Hybrid MPI and Low-Field MRI Scanner
No full textMagnetic particle imaging (MPI) offers high contrast and sensitivity in imaging the spatial distribution of the magnetic nanoparticles (MNPs), since only the MNPs contribute to the signal and the human tissue does not. In return, MPI lacks anatomical information, which needs to be provided by another imaging modality such as magnetic resonance imaging (MRI). Recently, we presented a preclinical-size open-sided hybrid MPI and low-field MRI (LF-MRI) scanner, in which the coils are used interchangeably between the two modalities. In this study, the transmit/receive chain for the LF-MRI mode is integrated into the hybrid system, and its LF-MRI performance is demonstrated with imaging experiments at a B0 field of 50 \mT
Magnetic particle spectroscopy based biosensing platform for nucleic acids detection
No full textReliable nucleic acid assays are essential for modern laboratory diagnostics. Due to the complex and numerous steps involved, polymerase chain reaction, the current gold standard in nucleic acid detection, is not suitable for point-of-care (POC) diagnostics. Assays based on magnetic nanoparticles (MNPs) and magnetic particle spectroscopy (MPS) are wash- and enzyme-free and combine signal amplification with a benchtop device, thus fulfilling all the requirements to close this gap. Our nucleic acids biosensing platform enables the specific detection of DNA in concentrations of less than 27 pM as well as the enzyme-free detection of viral RNA in combination with a highly sensitive MPS device with cost-effective technology
Advancing brain drug delivery: Focused magnetic hyperthermia and magnetic particle imaging for real-time BBB modulation: Focused magnetic hyperthermia and magnetic particle imaging for real-time BBB modulation
No full textAbstractThe blood-brain barrier (BBB) is crucial for brain protection but limits therapeutic delivery for neurological disorders. This study utilizes magnetic hyperthermia (MH) to transiently and reversibly open the BBB, with magnetic particle imaging (MPI) enabling real-time, high-sensitivity monitoring. Using field-free point (FFP)-based focused heating, MH facilitated magnetic nanoparticles (MNPs) penetration into the brain and prolonged retention in the target area. IVIS imaging confirmed increased BBB permeability immediately after MH, while MPI quantification revealed significant MNPs accumulation at target sites in focused-heated groups compared to non-heated controls. IVIS images further showed that BBB permeability restored after 24 hours, though MNPs retention persisted in heated regions for more than 72 hours. IVIS imaging confirms BBB permeability immediately after MH, while MPI provides both qualitative imaging and quantitative data on MNPs distribution and retention. These findings indicate that MPI can detect particle retention and distribution patterns that are not visible with IVIS imaging
Degradation characteristics of PLA-based medical implant markers for Magnetic Particle Imaging
No full textPotential clinical applications for Magnetic Particle Imaging (MPI) include cardiovascular imaging and endovascular interventions. To visualize medical instruments in MPI, permanent marking technologies have been developed. However, to prevent artefacts during follow-up examinations, temporary markers are of interest, e.g. for postinterventional stent lumen quantification. In this work, biodegradable medical instrument markers, based on polylactic acid (PLA) and superparamagnetic iron-oxide nanoparticles (SPIONs), have been developed. The markers’ signal characteristics and degradation were investigated over a period of 28 d in a water bath at 37 °C. Analysis was conducted using a laboratory scale, Micro-CT, microscopy, Magnetic Particle Spectroscopy (MPS), MPI and Vibrating Sample Magnetometry (VSM). The mass of the markers decreased by ~90% after 28 d. However, no signal loss or relevant loss of SPIONs was detected. This contradictory behavior is surprising and requires further investigation
Towards SPION-Enhanced Real-Time Visualization of Onyx Embolization
No full textMagnetic particle imaging (MPI) is emerging as a promising technique for various clinical applications, including real-time monitoring of endovascular interventions. The use of liquid embolic agents is established for the therapy of vascular pathologies, e.g. malformations. To identify the timepoint of complete hardening is essential for the safe and effective use of such liquid embolization materials. In this study, we aimed to monitor the solidification process of the liquid embolic agent Onyx-20 by integration of superparamagnetic iron oxide nanoparticles (SPIONs). Our findings suggest that the observed differences in the magnetic signal throughout the solidification process are particularly advantageous for the application of multi-contrast MPI techniques, potentially enhancing the monitoring of embolization procedures
A three-dimensional arbitrary waveform MPS for MPI scanner concept evaluation
No full textWe present the first three-dimensional Arbitrary Waveform Magnetic Particle Spectrometer (3D-AWMPS), opening new applications of magnetic particle spectroscopy in both particle analysis and scanner concept emulation. With three orthogonal field channels, capable of arbitrary waveform excitation with frequencies from DC to more than 150 kHz, any field sequence present in typical MPI systems can be applied to the particles, measuring the scanners signal encoding properties. We report a first system matrix measurement emulating a hypothetical FFL scanner