MULTIFREQUENCY INTERPOLATION FOR FAST OFF-RESONANCE CORRECTION

Field inhomogeneities or susceptibility variations produce blurring in images acquired using non-2DFT k-space readout trajectories, This pro blem is more pronounced for sequences with long readout times such as spiral imaging. Theoretical and practical correction methods based on an acquired field map have been reported in the past. This paper intro duces a new correction method based on the existing concept of frequen cy segmented correction but which is faster and theoretically more acc urate, It consists of reconstructing the data at several frequencies t o form a set of base images that are then added together with spatiall y varying linear coefficients derived from the field map, The new algo rithm is applied to phantom and in vivo images acquired with projectio n reconstruction and spiral sequences, yielding sharply focused images .