Reconstructing MR images from undersampled data: Data-weighing considerations

Data which are sampled more densely than the Nyquist limit in k-space are weighted prior to reconstruction by the inverse of the local sampling density. This work considers the effects of weighing data that are sampled less densely than the Nyquist limit. It specifically analyzes azimuthally undersampled projection reconstruction, variable density spirals, and variable density phase encoding. Effects on resolution, aliasing, and SNR are given. Higher resolution is obtained by weighing undersampled data according to the inverse of sampling density, while better SNR and less aliasing artifact are obtained by weighing undersampled data uniformly. (C) 2000 Wiley-Liss, Inc.