Magnetic Particle Imaging tracks the long-term fate of in vivo neural cell implants with high image contrast.

We demonstrate that Magnetic Particle Imaging (MPI) enables monitoring of cellular grafts with high contrast, sensitivity, and quantitativeness. MPI directly detects the intense magnetization of iron-oxide tracers using low-frequency magnetic fields. MPI is safe, noninvasive and offers superb sensitivity, with great promise for clinical translation and quantitative single-cell tracking. Here we report the first MPI cell tracking study, showing 200-cell detection in vitro and in vivo monitoring of human neural graft clearance over 87 days in rat brain

Correction of Blurring due to a Difference in Scanning Direction of Field-Free Line in Projection-Based Magnetic Particle Imaging

In projection-based magnetic particle imaging (MPI) with a field-free-line (FFL) encoding scheme, projection data are usually acquired by moving the FFL in a zigzag and a difference in the projection data occurs depending on the scanning direction of FFL, resulting in blurring in the reconstructed images. In this study, we developed a method for correcting the blur by deconvolution using a signal-delay constant ({\xi}). The {\xi} value for correction ({\xi}c) was determined by acquiring projection data in positive and negative directions and searching for the {\xi} value which minimized the 2-norm between the deconvolved projection data in the two directions. We validated our method using a line and A-shaped phantoms for various velocities of FFL (vFFL). The {\xi}c value correlated linearly with vFFL. The full width at half maximum of the line phantom decreased significantly after correction of the blur. The effectiveness of our method was also confirmed by the MPI images of the A-shaped phantom. These results suggest that our method will be useful for enhancing the reliability of projection-based MPI

First energetic neutral atom images from Polar

Energetic neutral atoms are created when energetic magnetospheric ions undergo charge exchange with cold neutral atoms in the Earth\u27s tenuous extended atmosphere (the geocorona). Since they are unaffected by the Earth\u27s magnetic field, these energetic neutrals travel away in straight line trajectories from the points of charge exchange. The remote detection of these particles provides a powerful means through which the global distribution and properties of the geocorona and ring current can be inferred. Due to its 2 × 9 RE polar orbit, the Polar spacecraft provides an excellent platform from which to observe ENAs because it spends much of its time in the polar caps which are usually free from the contaminating energetic charged particles that make observations of ENAs more difficult. In this brief report, we present the first ENA imaging results from Polar. Storm-time ENA images are presented for a northern polar cap apogee pass on August 29, 1996 and for a southern polar cap perigee pass on October 23, 1996. As well, we show with a third event (July 31, 1996) that ENA emissions can also be detected in association with individual substorm

3D reconstruction of magnetization from dichroic soft X-ray transmission tomography

The development of magnetic nanostructures for applications in spintronics requires methods capable of visualizing their magnetization. Soft X‐ray magnetic imaging combined with circular magnetic dichroism allows nanostructures up to 100–300 nm in thickness to be probed with resolutions of 20–40 nm. Here a new iterative tomographic reconstruction method to extract the three‐dimensional magnetization configuration from tomographic projections is presented. The vector field is reconstructed by using a modified algebraic reconstruction approach based on solving a set of linear equations in an iterative manner. The application of this method is illustrated with two examples (magnetic nano‐disc and micro‐square heterostructure) along with comparison of error in reconstructions, and convergence of the algorithm