High Resolution Enlarged Open-Bore Narrow-band Magnetic Particle Imaging Based on Double-layer Linear Scanning Structure

We developed a novel high resolution open-bore narrowband magnetic particle imaging (MPI) system for big animal and future clinical usage. Optimized strength and direction of excitation field was invested for enlarged field of view (FOV), and a 4T/m gradient field as well as its linear scanning trajectory were formed by 16 square coils without coupling to excitation, forming a maximum 120mm×120mm open bore FOV. Further, a new differential pick-up structure consisted of multi Helmholtz excitation and pickup coils away from the FOV was proposed in order to suppress the system noises, which was very important for the limited coil setting space in open-bore MPI. The new differential structure contributed significantly to improve the signal-to-noise ratio as high as about 100dB without lose of harmonic signals. Several home-made resonant circuits, filters and lock-in amplifier was used to constitute the high precision signal acquisition system. Experimental results showed that the detection limit of the system was 1ug Fe of Resovist sample with a spatial resolution of 1mm after reconstruction, satisfying many clinical needs such as drug delivery and bedside-monitoring.