Effects of Drive Field Parameters in Magnetic Particle Imaging: A Relaxometer Study

In Magnetic Particle Imaging (MPI), it is possible to acquire signal from the nanoparticles via applying oscillating magnetic fields in the 1 kHz -150 kHz frequency range . Though 25 kHz is commonly used, there are not enough studies on determining the optimal excitation frequency and excitation strength for obtaining images of high quality. In this study, we observed nanoparticles’ response and the effect on the point spread functions (PSF) at various field amplitudes and at 10 kHz, 25 kHz and 148.5 kHz excitation frequencies. Accordingly, at 10 kHz and 25 kHz both the harmonic response of the nanoparticles and the PSFs are largely similar. On the other hand, the frequency components at 148.5 kHz are decreasing rapidly at increasing harmonics. The larger full-width at half-maximum of the obtained PSF indicates that the image resolution of this image will be lower at this frequency.