1D imaging of a superparamagnetic iron oxide nanoparticle distribution by a single-sided FFL magnetic particle imaging scanner.

Magnetic Particle Imaging (MPI) is an emerging imaging modality that has a potential of complimenting other imaging modalities in clinical practice. Despite many efforts to scale up MPI hardware to date no MPI systems have been demonstrated to accommodate full body imaging. Previously, we introduced hardware and characterized a prototype of a single-sided MPI scanner, where all coils are confined to a single-side of the device, which provides a subject with unrestricted access to the scanning area although with a limited penetration depth. The major difference in our design from the first reported single-sided scanner is in incorporating a field-free line instead of a field-free point, which generally promises higher sensitivity and more robust image reconstruction. However, as inherent to any single-sided configurations the fields in our device are spatially inhomogeneous making it challenging to apply existing imaging techniques. For our specific geometry we implemented spatial encoding scheme and imaging in time-domain making the image reconstruction fast. In this work we present one dimensional imaging of multiple rods phantoms with a single-sided field-free line MPI scanner. The results demonstrate that our scanner is capable of one dimensional imaging of phantoms with a spatial resolution of at least 7 mm without image processing.

2D projection image reconstruction for field free line single-sided magnetic particle imaging scanner: simulation studies.

Magnetic Particle Imaging is an imaging modality that exploits the nonlinear response of superparamagnetic iron oxide nanoparticles to a time-varying magnetic field. In the past years, various scanner topologies have been proposed, which includes a single-sided scanner. Such a scanner features all its hardware located on one side, offering accessibility without limitations due to the size of the object of interest. In this paper, we present a proof of concept image reconstruction simulation studies for a single-sided field-free line scanner utilizing non-uniform magnetic fields. Specifically, we implemented a filtered backprojection algorithm allowing a 2D image reconstruction over a field of view of 4 × 4 cm2 with a spatial resolution of up to 2 mm for noiseless case.

Single-Sided Magnetic Particle Imaging Device with Field-Free-Line Geometry for in-vivo Imaging Applications.

Magnetic Particle Imaging (MPI) has shown great promise to surpass existing in vivo imaging modalities in some clinical applications. However, one of the challenges to MPI being translated into clinical practice has been the ability to scale up the selection field coils to surround a human body while being able to generate and drive a sufficiently strong magnetic field gradient. These requirements impose safety concerns as well as prohibitively high-power consumption in devices with large cylindrical volume. Therefore, we consider an alternative approach such as a single-sided topology, in which all the hardware is located on one side of the imaging volume accommodating larger subjects. Moreover, different from the previously implemented field-free point single-sided scanners, we realized a field-free line geometry providing, in principle, factor of ten higher signal and benefiting from a more robust back-projection image reconstruction technique. In this work, we present and characterize a first prototype of a single-sided MPI device with field-free-line geometry suited for in-vivo imaging of small animals as well as regions of interest in humans.

Perfluorinated alkyl acids and fecundity assessment in striped mullet (Mugil cephalus) at Merritt Island national wildlife refuge.

This study investigated wild caught striped mullet (Mugil cephalus) at Merritt Island National Wildlife Refuge (MINWR) for levels of 15 perfluoroalkyl acids (PFAA) in tandem with individual fecundity measurements (Oocyte sub-stage 2 late, n=42) and oocyte reproductive stages (Stages 1-5, n=128). PFAA measurements were quantified in striped mullet liver (n=128), muscle (n=49), and gonad (n=10). No significant negative impacts of liver PFAA burden on wild-caught, mullet fecundity endpoints were observed in this study; however, changes in PFAA were observed in the liver as mullet progressed through different sub-stages of oocyte development. Of the PFAA with significant changes by sub-stage of oocyte development, the carboxylic acids (perfluorooctanoic acid, perfluorononanoic acid, and perfluorotridecanoic acid) increased in the liver with increasing sub-stage while the sulfonic acid and its precursor (perfluorooctanesulfonic acid (PFOS) and perfluorooctanesulfonamide, respectively) decreased in the liver with increasing sub-stage of oocyte development. This is a unique find and suggests PFAA change location of compartmentalization as mullet progress towards spawning. Investigations also revealed higher than expected median muscle and gonad levels of PFOS in striped mullet collected at MINWR (9.01ng/g and 80.2ng/g, respectively).