International Journal on Magnetic Particle Imaging (IJMPI)
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Multiparametric rotational drift spectroscopy
No full textRotational Drift Spectroscopy (RDS) is a novel spectroscopic method for magnetic nanoparticles. It is based on measuring the rotational drift of magnetic nanoparticle ensembles in a rotating magnetic field, which is below the magnetic field strength necessary for rotating the magnetic nanoparticles synchronously. The resulting asynchronous rotational drift strongly depends on the properties of the magnetic nanoparticles and their environment. This provides a promising basis for spectroscopic measurements with high sensitivity as well as high specificity, e.g., detecting specific molecules in a liquid via functionalized magnetic nanoparticles. In this work, multiparametric Rotational Drift Spectroscopy (mRDS) is presented, which makes use of the nonlinear dependency of the RDS signal of, e.g., the sequence amplitude and the viscosity of the suspending liquid of the magnetic particle sample. This allows access to a variety of parameters of magnetic nanoparticle suspensions
iMPI – interventional Magnetic Particle Imaging
No full textMagnetic Particle Imaging (MPI) has become a promising candidate for medical applications, especially cardiovascular interventions. Necessary milestones have been reached in multiple pre-clinical experiments and studies and are ready to be tested on human-scale MPI scanners. Only few human-sized scanner systems designed for dedicated applications are available. In this abstract, a novel approach is presented for a dedicated human-sized interventional MPI scanner
Improvement study of Field-Free Line Generator for mechanically scanned-type MPI system
No full textWe proposed hybrid field free line(H-FFL) generator that is compact and has low power consumption in 2020. In this paper, we summarized the development process and advantages of new type of FFL generator that outperform the previous H-FFL generator. The FFL generator not only shows 1.83 times higher the magnetic gradient field but also decrease the total volume and weight to be 1/3. In addition, it is designed to be easier and cheaper to manufacture
Lissajous trajectory magnetic particle imaging for image-guided hyperthermia therapy and monitoring
No full textMagnetic field hyperthermia (MFH) therapy is an emerging cancer treatment which uses heat to damage tumors. Like magnetic particle imaging (MPI), MFH combines injected magnetic nanoparticles with the subsequent application of time-varying magnetic fields. One potential application of MPI technology is in aiding the optimization and safety of MFH therapy. This work reports recent successes in demonstrating how Lissajous scanning magnetic particle imaging can act as a multi-functional platform to support the safe and optimized application of MFH therapy. Lissajous scanning MPI can i) image magnetic nanoparticles in-vivo to verify that they are correctly located within the tumor tissue before heat generation begins, ii) generate spatially-focused heating using the Lissajous scanning magnetic field sequences iii) produce 3D images of the elevated temperatures generated during therapy in real-time. Recent achievements in developing the capability for realizing accurately calibrated temperature-resolved 3D “multi-colour” Lissajous MPI via the system matrix technique are also reported
Elucidating super-resolution Magnetic Particle Imaging: superferromagnetic remanence decay through MPI signal evolution informs super-resolution MPI scan strategies
No full textMagnetic particle imaging (MPI) is a tracer imaging modality that detects superparamagnetic iron oxide nanoparticles (SPIOs), enabling sensitive, radiation-free imaging of cells and disease pathologies. Preclinical MPI resolution is limited to ~1-2 mm (with ferucarbotran) due to scanner and particle constraints. Recent SPIOs have shown 10-fold resolution and signal improvements at high concentrations, with unusually sharp magnetic responses. Dubbed superferromagnetic iron oxide particles (SFMIOs), these particles appear to interact with neighbours, effectively amplifying applied fields. SFMIO signal is highly dependent on the remanence of magnetically-generated SFMIO superstructures. This work explores SFMIO remanence evolution after magnetic polarization, showing zero-field decay around 120 ms, and various strategies for maintaining SFMIO behaviour that set the minimum scan speed for in vivo usage. The resolution improvements provided by generating and maintaining SFMIO superstructures will allow for 10-fold reduction in scanner field strength and thus a 100-fold reduction in cos
Influence of reaction parameters on the synthesis of silica-coated superparamagnetic iron oxide particles
No full textSuperparamagnetic iron oxide nanoparticles (SPIONs) are playing an increasingly important role in medical technology. They can serve as tracers for the new imaging modality Magnetic Particle Imaging (MPI), magnetic beats for magnetic cell separation, or for hyperthermia treatment of tumorous tissue. Of particular interest are their unique magnetic properties. These are based on the morphology of a particle core consisting of iron oxide, encased in a biocompatible material. Through the synthesis process, both the size of the core and the nature of the silica coating material can be controlled. The influence of the synthesis parameters on the magnetic and size properties of the SPIONs will be investigated
Saturation Coil for Localized Suppression in MPI
No full textThe magnetic nanoparticles (MNPs) used as imaging tracers in magnetic particle imaging (MPI) accumulate in off-target organs such as liver or spleen. The signal from the high-concentration MNPs in these off-target organs may overpower the signals from the nearby low-concentration regions targeted during imaging. In this work, we propose using a saturation coil to suppress the localized high intensity MPI signal from the off-target accumulation organs. The results of the proof-of-concept imaging experiments show that, when the saturation coil is placed over the high-concentration region, it can selectively and completely suppress the signal from that region
Fast and artifact reducing joint multi-patch MPI reconstruction
No full textThe method of magnetic particle imaging has a limited field of view due to physiological constraints. It is thus necessary to enlarge the field of view by a multi-patch approach in order to cover larger volumes. During reconstruction, truncation artifacts arise at the patches boundaries. We apply stochastic primal-dual hybrid gradient method to jointly reconstruct multi-patch magnetic particle images. We are thus able to apply a regularization, which takes into account neighborhood structures, not only on one patch but over all patches. Our experiments show that the quality of our reconstructions is significantly higher than the ones of reconstructions obtained by Kaczmarz method. Moreover, a joint reconstruction can considerably reduce the computational costs compared to multiple single-patch reconstructions
MPI-based spatio-temporal estimation of a temperature profile induced by an IR laser
No full textThe separation of signals based on particle type, their environment or temperature has added a useful layer to the foundation of spatial MP imaging. The multi-color approach of signal reconstruction offers a far-reaching option for clinical interventions such as the controllable and precise application of hyperthermia. In this study, a multi-color reconstruction approach was applied to highlight the potential of MPI for temperature monitoring. For this purpose, we heated a solution of SPIO nanoparticles with a high-power laser and reconstructed the corresponding dynamic temperature maps by MPI data acquisition. A good temporal and spatial correlation between the MPI-based temperature maps and fiber optic thermometer measurements was observed
A Flexible High-Performance Signal Generation and Digitization Plattform based on Low-Cost Hardware
No full textModern imaging modalities, such as magnetic particle imaging (MPI), are based on complex sequences which require synchronous multi-channel signal generation and reception. The component of an MPI scanner responsible for this functionality is the data acquisition (DAQ) system. Different scanner topologies and the nature of (digital) signal processing impose varying requirements on such a system. In this work, we introduce the RedPitayaDAQServer project, which implements a flexible scalable DAQ system. It is based on the low-cost hardware RedPitaya STEMlab 125-14 and is able to meet the requirements of most MPI scanner concepts that have been proposed to date