Point-wise k-space evaluation for spatial encoding magnetic fields for magnet optimizations

Motivation: The current optimizations of permanent magnet array (PMA) designs are guided by checking field properties, not reflecting the quality of reconstructed images. Goal(s): We aim to propose indicating parameters for the encoding capability of spatial encoding magnetic fields (SEMs) to guide PMA designs. Approach: Local k-spaces are pushed to be point-wise. The coverage area of the point-wise k-spaces between the spokes of the maximum and minimum angles is calculated to indicate the encoding capability. Results: The proposed method is fast, enlarging the optimization space, resulting in SEMs having superior encoding capability with stronger field, higher gradient, and lower NRMSE of the resultant images. Impact: The proposed point-wise k-space evaluation enlarges the solution space for the PMA optimizations thus significantly improves the performances of the outcomes, i.e., SEMs having superior encoding capability with higher field strength and higher gradient compared to that from conventional approachs.