Imaging Characterization of MPI Tracers Employing Offset Measurements in a two Dimensional Magnetic Particle Spectrometer

Abstract

We developed a method to characterize the imaging performance of MPI tracers from virtual MPI measurements that can be synthesized using measurement data from a Magnetic Particle Spectrometer (MPS) at different static magnetic field offsets. MPI system functions were obtained from measurements on a FeraSpin™ R (nanoPET GmbH, Berlin) sample in a 2D MPS comprising two excitation coils and two receive coils. Software phantoms of spatial MPI tracer distributions with different size and shape were constructed. With the measured MPI system function, a synthetic MPI measurement of the software phantoms was simulated. By adding noise to the virtual MPI data, the detection limit of each harmonic in dependence of the noise level was obtained. An MPI reconstruction of the virtual tracer distribution was performed using the virtual MPI data as input. By comparing the reconstructed images with the actual software phantoms, we obtained the spatial resolution of MPI of the investigated tracers. This method might help predicting the image resolution for real MPI setups. Our characterization method provides a valuable link between pure spectroscopic characterization and time consuming MPI phantom experiments.