Direct magnetic field compensation using multichannel digital-to-analog converter for magnetic particle imaging with detection coil array

Magnetic particle imaging (MPI) is an imaging diagnostic method that uses magnetic nanoparticles (MNPs). In this method, the magnetic field that excites the MNPs induces fundamental components in the detection coils owing to the direct magnetic field linkage, which adversely affects the measurements. In previous studies, this effect was mitigated by using a single-channel digital-to-analog (D/A) converter and instrumentation amplifier for compensation. Because multiple detection coils were used, variable resistors were employed to adjust the fundamental components of each channel. However, this process is time-consuming and does not allow phase adjustment, leading to reduced accuracy. This study proposes a compensation circuit using a multichannel D/A converter, that enables voltage adjustment for each channel via software. The proposed signal processing circuit significantly improved the compensation accuracy and successfully enabled position estimation within a 10 mm error when the sample was located 40 mm deep in the z-direction relative to the detection coils. These results demonstrate the feasibility of performing MPI using the proposed circuit.