Motivation: To propose a new permanent magnet array with high field homogeneity and compatible with existing MRI technologies. Goal(s): Our goal was to design an asymmetric permanent magnet array to significantly improve the field homogeneity and make it easier to manufacture. Approach: The proposed permanent magnet array incorporates an asymmetric arrangement of magnet elements, combining elliptical and circular arrays. Additionally, shim magnets and multi-coil are employed to improve the homogeneity. Results: The proposed array produces a field with an average strength of 55 mT and an inhomogeneity of 16984 ppm within 20 cm DSV. After shimming, the inhomogeneity was reduced to 3665 ppm. Impact: The proposed asymmetric permanent magnet array significantly improves homogeneity, making it a promising option for portable MRI brain imaging system.
Shao et al. (2025) studied this question.