Resistive homogeneous MRI magnet design by matrix subset selection

A new technique for designing resistive homogeneous multicoil magnets for m agnetic resonance imaging (MRI) is presented. A linearly independent subset of coils is chosen from a user-defined feasible set using an efficient num erical algorithm, The coil currents are calculated using a linear least squ ares algorithm to minimize the deviation of the actual magnetic field from the target field. The solutions are converted to practical coils by roundin g the currents to integer ratios, selecting the wire gauge, and optimizing the coil cross-sections, To illustrate the technique, a new design of a sho rt, homogeneous MRI magnet suitable for low-field human torso imaging is pr esented. Magnets that satisfy other constraints on access and field uniform ity can also be designed. Compared with conventional techniques that employ harmonic expansions, this technique is flexible, simple to implement, and numerically efficient. (C) 1999 Wiley-Liss, Inc.