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Complex Relationship Between Signal Intensity Properties in Magnetic Particle Imaging (MPI) and Iron Oxide Nanoparticle Degradation

revised on 18.02.2020, 16:19 and posted on 19.02.2020, 08:39 by Julia Guzy, Shatadru Chakravarty, Foster Buchanan, Haoran Chen, Jeffrey M. Gaudet, Jeremy Hix, Christiane L. Mallett, Erik Shapiro
Magnetic particle imaging (MPI) is an exciting new biomedical imaging technology that uses superparamagnetic nanoparticles as an imaging tracer. MPI is touted as a quantitative imaging modality but MPI signal properties have never been characterized for nanoparticles undergoing biodegradation. Here we characterize the nature of the MPI signal properties as a function of degradation of various magnetic particle formulations. We show that MPI signal properties can increase or decrease as a function of nanoparticle formulation and chemical environment and that long-term in vitro experiments only roughly approximate long-term in vivo MPI signal properties. Data are supported by electron microscopy of nanoparticle degradation. Knowledge of MPI signal property changes during nanoparticle degradation will be critical in design and interpretation of all MPI experiments. Further, we demonstrate for the first time, an environmentally sensitive MPI contrast mechanism opening the door to smart contrast paradigms in MPI.


Email Address of Submitting Author


Michigan State University


United States

ORCID For Submitting Author


Declaration of Conflict of Interest

Authors Chakravarty and Shapiro have pending patents on the PLGA-encapsualted iron oxide nanoparticles described herein and Shapiro is Founder and President of Shape Scientific, supplier of the iron oxide nanocrystals and CLIPs used in these studies.