Single harmonic-based narrowband magnetic particle imaging

Magnetic particle imaging (MPI) quantitatively visualizes in vivo superparamagnetic iron oxide nanoparticles (SPIONs), which has shown great promises in biomedicine. In this paper, we propose a single harmonic-based narrowband MPI approach via measuring a single harmonic—3f0 harmonic—of the SPIONs induced in an excitation magnetic field with frequency f0 = 5 kHz. The narrowband MPI scanner is built to scan the field-free-point, generated by a pair of permanent magnets, through an imaging field-of-view, and to measure the magnetic response of the SPIONs by a narrowband receive system. The narrowband MPI approach dramatically reduces the design efforts in the transmit system and noise matching in the receive system. Phantom experiments are performed with the custom-built narrowband MPI scanner to evaluate the spatial resolution and limit of detection (LOD). Experimental results indicate that the proposed single harmonic-based narrowband MPI approach allows a spatial resolution of 0.5 mm and an LOD of 27 μg (Fe) ml−1 (254 ng Fe weight) using Perimag® SPIONs, which can significantly be improved by using optimized SPIONs and by improving the detection circuitry. We believe that the proposed narrowband MPI approach minimizes the MPI hardware efforts but still allows for good performance in terms of spatial resolution and LOD.