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Copyright (c) 2022 K. L. Barry Fung, Caylin Colson, Jacob Bryan, Benjamin D. Fellows, Chinmoy Saayujya, Prashant Chandrasekharan, Carlos Rinaldi, Steven Conolly
This work is licensed under a Creative Commons Attribution 4.0 International License.
Magnetic particle imaging (MPI) is a tracer imaging modality that detects superparamagnetic iron oxide nanoparticles (SPIOs), enabling sensitive, radiation-free imaging of cells and disease pathologies. Preclinical MPI resolution is limited to ~1-2 mm (with ferucarbotran) due to scanner and particle constraints. Recent SPIOs have shown 10-fold resolution and signal improvements at high concentrations, with unusually sharp magnetic responses. Dubbed superferromagnetic iron oxide particles (SFMIOs), these particles appear to interact with neighbours, effectively amplifying applied fields. SFMIO signal is highly dependent on the remanence of magnetically-generated SFMIO superstructures. This work explores SFMIO remanence evolution after magnetic polarization, showing zero-field decay around 120 ms, and various strategies for maintaining SFMIO behaviour that set the minimum scan speed for in vivo usage. The resolution improvements provided by generating and maintaining SFMIO superstructures will allow for 10-fold reduction in scanner field strength and thus a 100-fold reduction in cost
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