Comparison of magnetostimulation limits for axial and transverse drive fields in MPI

As shown in Fig. 1b, the mean magneto stimulation thresholds for the transverse field was approximately 3 times lower than the axial field (ΔB
_min
= 26 mT-pp vs. 78 mT-pp) for the same set of subjects, with comparable τc values (265 μs vs. 243 μs). In addition, the percentage deviation across subjects was significantly smaller for the transverse field (13%) than the axial field (28%). For both transverse and axial fields, the data trends were well modeled by the hyperbolic amplitude vs. frequency curve, as demonstrated in Fig. 1c for a single subject.