Tracer Characterization and Signal Quantification in Magnetic Particle Imaging

Magnetic particle imaging (MPI) is the only biomedical imaging technology where signal arises solely from the unique nonlinear magnetic response of engineered exogenous nanoparticles. Because the signal is proportional to the mass of the magnetic nanoparticle tracer and because there is no signal attenuation or tissue-associated background, MPI has exciting applications where non-invasive, unambiguous, and quantitative information is required of the nanoparticle distribution in living subjects. This includes applications in tracking adoptive cell therapies, monitoring nanoparticle drug carriers, and interrogating pathological phenomena such as inflammation and bleeding. Tracer development, and consequently tracer characterization and signal quantification are essential steps in these and other applications. However, the field lacks standards to harmonize studies across multiple labs with differing levels of MPI expertise and instrumentation access. This talk will summarize my group's experience in developing methods to characterize MPI tracers and in quantifying their signal in ex vivo phantoms and in living subjects, with the goal of providing guidance and best practice for others in the field.