Magnetic Particle Imaging System Utilizing Orthogonal Gradient Field and Harmonic Signal Detection

We developed a magnetic particle imaging (MPI) system using harmonic signal detection. To improve the spatial resolution, we added an orthogonal gradient magnetic field to MPI system. Two adjacent magnetic nanoparticle samples were detected using the second and third harmonic signals, which were generated from the nonlinear magnetization of particles. We found that the spatial resolution significantly improved by using the gradient magnetic field in each case without affecting the strength of the signals. Two samples, which located at distance of Z = 28 mm with separation of δ =20 mm, were clearly identified. Since the second harmonic signal showed complicated behavior when distance Z changed, third-harmonic signal detection is suitable for the MPI application