International Journal on Magnetic Particle Imaging (IJMPI)
Not a member yet
555 research outputs found
Sort by
A magnetic immunization method based on magnetic nanomarkers under the DC bias field
No full textThis paper investigates the effect of the SNR of the magnetic response harmonic signal on the sensitivity of biomolecular detection. A method is proposed for measuring the 2nd and 3rd harmonics of magnetic nanotags under a DC bias field, avoiding the influence of antimagnetic and paramagnetic substances around the magnetic nanotags, as well as the background magnetic field, on the 1st harmonic signal. Specific streptavidin-modified magnetic nanoparticles were used as measurement objects, and their binding to biotinylated polystyrene microspheres was measured by a prepared detection device to simulate the detection of specific biomolecules. Using the 2nd to 3rd harmonic ratio, the lower limit of detection of the lowest 4amol (0.4pM) polystyrene microspheres in a 100uL solution was eventually determined
Image Reconstruction in Magnetic Particle Imaging Based on Gaussian Weighted Laplace Prior Regularization
No full textMagnetic particle imaging (MPI) is an emerging tomographic imaging modality with high spatial and temporal resolution. The image reconstruction in MPI needs to solve an ill-posed inverse problem. Tikhonov regularization is known to solve this kind of problems. However, the traditional Tikhonov regularization (L2 regularization) guides the reconstruction to be over smooth and tends to generate a lot of low-value noise in the background. In this work, we develop an efficient and noise reducing reconstruction method for MPI. We proposed a Gaussian weighted Laplace regularization which assumes that the correlation between any two voxels inside the field of view (FOV) has a non-linear inverse relationship with their spatial distance. Experimental results show proposed method can provide more accurate MPI reconstruction
First Complex Trials Using a Dedicated Balloon Catheter for Magnetic Particle Imaging
No full textA recent work introduced a balloon catheter from a polymer mixed with magnetic nanoparticles that was visible in magnetic particle imaging (MPI) in initial trials. In this work, dynamic multi-patch and multi-contrast experiments were performed to validate the usability of the balloon catheter for complex application scenarios. In both cases, the balloon was successfully imaged, although there are limitations in resolution and dynamic imaging range
FMMD controller and software for MPI system based on mechanical FFL movement
No full textWe describe FMMD controller and software for MPI system based on mechanical FFL movement. MPI based on mechanical FFL movement requires signal processing such as signal excitation, amplification, filter, and acquisition. And it is essential to synchronize the acquired signal with the mechanical FFL movement. For signal processing, FMMD controller that can adjust the attenuation and amplification factors and filtering frequencies of signals in real time was used. The signal acquired from the controller was transferred to the host PC, and the synchronization between the signal acquired from the MPI device and the mechanical FFL motion was processed, and the frequency analysis of the synchronized data was performed in software. Without using various commercial signal processing equipment, we were able to develop MPI system by using the controller and software
Characterizing the performance of commercial magnetic particles for magnetic particle imaging
No full textThe properties of magnetic nanoparticles (MNPs) are key to the effectiveness of magnetic particle imaging (MPI). While commercial MNPs are used extensively in clinical and research applications, there are still challenges in understanding the effect of certain MNP properties on its resolution and sensitivity. Being able to understand these trends will enhance efforts in optimizing parameters in MNP production for specific applications. In this study, we looked at MNP core size, clustering, and coating and their effects on its FWHM, and compared the sensitivity of different commercial particles. We identified a trend in FWHM and MNP core size as well as effects of certain coating on FWHM
Dedicated Interventional Instruments for Magnetic Particle Imaging
No full textVascular interventions are a very promising application of Magnetic Particle Imaging. The possibility to visualize the devices is a prerequisite for diagnosis and treatment of vascular diseases. In this contribution, we present a balloon catheter from a polymer mixed with nanoparticles. A dynamic imaging is performed to show that the inflation and deflation of the balloon can be imaged with MPI
Traveling Wave MPI utilizing a Field-Free Line
No full textField-free line (FFL) Magnetic Particle Imaging (MPI) scanners are of high interest for fast and accurate scanning of 3D samples because of the higher signal-to-noise ratio due to the enlarged encoding scheme. Until now, only magnetic field generators have been presented providing an electrical rotation and displacement of an FFL within a 2D slice. Utilizing double-helix coils and the Traveling Wave approach, a full 3D FFL MPI scanner can be introduced, providing fast 3D imaging with less hardware efforts
Low-Power Iron Selection and Focus Field Generator
No full textA major issue for human-sized Magnetic Particle Imaging (MPI) scanners is the generation of sufficiently large magnetic gradient fields. By taking advantage of the field amplification properties of soft iron, a considerable amount of power can be saved. In this work, an optimized selection and focus field generator is presented, that can generate flexible and high gradient fields at comparatively low power consumption. Coil spacing and possible field-free-point positions are similar to conventional MPI scanners designed with air coils, but with significantly less demands on infrastructure and cooling design. The optimization process is discussed and first field measurements are presented
A microrobot for endovascular aneurysm treatment steered and visualized with MPI
No full textThe steering of microrobots by using magnetic fields offers applications for minimally invasive surgery or for establishing drug delivery scenarios. On the one hand, magnetic particle imaging (MPI) offers a tomographic, real-time visualization of the used magnetic microrobots. On the other hand, an MPI scanner can apply magnetic fields, which a microrobot can be steered with. Hence, MPI is of great interest for realizing the tracking and navigation of microrobots. Here, we show that a microrobot, which has been coated with superparamagnetic iron oxide nanoparticles (SPIONs) can be steered through a patient specific phantom of the middle cerebral artery into an aneurysm, where it should occlude the aneurysm and can be potentially used for a triggered drug release or a hyperthermia treatment. The acquired MPI images show that a tracking accuracy of 0.68 mm is achieved.  
Magnetic signal evaluation and imaging of magnetic nanoparticles in brain phantom
No full textMagnetic Particle Imaging (MPI) is an imaging modality that directly detects the nonlinear response of magnetic nanoparticles (MNPs). Spatial encoding is realized by saturating the magnetic moment of MNPs most everywhere except in the special point called the field free reagion in which magnetic field vanishes. Recently, it has been shown that the sensitivity of MPI can be improved by using a field free line (FFL) in which the field free region formed as a line. We developed a MPI equipmemt with FFL using a neodymium magnet and an iron yoke, and magnetic particle imaging of a mouse brain phantom was successfully performed. In addition, we studied the magnetization response of MNPs in the brain and found that the magnetic response of magnetic moment to external magnetic field in the brain is different from that in buffer solution