Parallel magnetic particle imaging.

Abstract

Magnetic Particle Imaging (MPI) is a promising tomographic method to visualize the distribution of superparamagnetic materials in three-dimensions. For encoding, a strong gradient represented by a field free point (FFP) or a field free line (FFL) is steered rapidly through the field of view (FOV), acquiring the signal successively. Conventional MPI scanners only provide a single FFP or FFL to sample the entire scan volume, which limits the size of the FOV and/or the temporal resolution. The alternative scanner concept of Traveling Wave MPI (TWMPI) uses a dynamic linear gradient array (dLGA) for dynamic FFP generation along the symmetry axis. The TWMPI scanner is capable of creating multiple FFPs simultaneously, and usually care is taken to locate only a single FFP in the desired FOV. In this manuscript, the concept of parallel MPI utilizing multiple FFPs simultaneously is introduced. For that, conceptual simulations are presented followed by reconstruction approaches for visualization of parallel MPI signals. In addition, an initial parallel MPI experiment with simultaneous acquisition of signals from two FFPs inside the FOV of the same scanner using two receive chains is demonstrated. This allows scanning a doubled FOV within the same acquisition time without sacrificing resolution compared to the standard TWMPI scanner.