Multichannel joint image reconstruction allows for artifact-free focused small field of view magnetic particle imaging

Abstract

AbstractMagnetic Particle Imaging (MPI) directly detects superparamagnetic iron oxide (SPIO) labeled cells. We have used MPI to detect SPIO-labeled dendritic cells (DC) migrated to the popliteal lymph nodes (pLN) after injection into the hind footpads. However, in some cases the low pLN signal could not be resolved from nearby higher footpad signal where window leveling to pLN signal oversaturated the footpad signal. The same limitation occurs when SPIO is injected intravenously, accumulates in the liver, and prevents isolation of regions of interest with lower signals. Previous studies have reported on the issue of resolving a wide range of differing iron concentration. A small focused field of view (FOV), to exclude high sources of nearby signal cannot be performed with the standard reconstruction algorithm equipped on the MomentumTM MPI scanner because it is assumed that there is no signal at the edge of the FOV and these values are set to zero for each line along the transmit axis. However, when there is signal at the FOV edge, an inverted negative artifact is created. The multichannel joint reconstruction method uses an iterative reconstruction technique to recover edge information using information from an orthogonal axis, preventing this artifact and allowing the user to prescribe a small FOV on the region of interest. Here we describe the implementation of this method to isolate and quantify low regions of MPI signal from higher regions.