DC Coil Arrays for Gradient Field Generation and Static Field Correction at Ultra-Low Field (54 mT) MRI

Motivation: Ultra-low field (ULF) MRI scanners are designed to be lightweight and compact devices. To decrease complexity and to improve performance, we propose a simple structure to replace gradient coils and to homogenize the static field. Goal(s): To assess whether a multi-DC coil array can generate gradient fields and improve B0 field homogeneity at ULF. Approach: We used electromagnetic simulations based on Biot-Savart law, to investigate the feasibility of synthesizing the gradient fields and homogenizing the static field without limiting the current supplied to the individual DC channels. Results: The proposed structure can synthesize gradient fields and reduce B0 field inhomogeneity within ±5% error. Impact: This work demonstrates the feasibility of a simplified DC coil structure to replace conventional gradient coils and introduces an effective approach for static field homogenization in ultra-low field MRI (54 mT).