Characterization of the Clinically Approved MRI Tracer Resotran for Magnetic Particle Imaging in a Comparison Study

Objective. The availability of magnetic nanoparticles with medical approvalfor human intervention is fundamental to the clinical translation of magneticparticle imaging (MPI). In this work, we thoroughly evaluate and compare themagnetic properties of an magnetic resonance imaging (MRI) approved tracer tovalidate its performance for MPI in future human trials. Approach. We analyzewhether the recently approved MRI tracer Resotran is suitable for MPI. Inaddition, we compare Resotran with the previously approved and extensivelystudied tracer Resovist, with Ferrotran, which is currently in a clinical phaseIII study, and with the tailored MPI tracer Perimag. Main results. Initialmagnetic particle spectroscopy measurements indicate that Resotran exhibitsperformance characteristics akin to Resovist, but below Perimag. We providedata on four different tracers using dynamic light scattering, transmissionelectron microscopy, vibrating sample magnetometry measurements, magneticparticle spectroscopy to derive hysteresis, point spread functions, and aserial dilution, as well as system matrix based MPI measurements on apreclinical scanner (Bruker 25/20 FF), including reconstructed images.Significance. Numerous approved magnetic nanoparticles used as tracers in MRIlack the necessary magnetic properties essential for robust signal generationin MPI. The process of obtaining medical approval for dedicated MPI tracersoptimized for signal performance is an arduous and costly endeavor, often onlyjustifiable for companies with a well-defined clinical business case. Resotranis an approved tracer that has become available in Europe for MRI. In thiswork, we study the eligibility of Resotran for MPI in an effort to pave the wayfor human MPI trials.