Linear projection method for automatic slice shimming.

A fast, reliable automatic slice shimming method is described. In-slice shim adjustments are based on one-dimensional phase mapping of four in-slice linear projections through the slice center. For axial, coronal, and sagittal slices it is shown that all in-slice first-, second-, and third-order spherical harmonic terms of B(0) inhomogeneity can be unequivocally determined and corrected. Through-slice shim adjustment is achieved using a one-dimensional projection of the entire slice or ROI along the slice-selection direction. Applications of this method to single-slice in vivo spectroscopic imaging of human brain have resulted in reproducible, high-quality spectroscopic data. Magn Reson Med 42:1082-1088, 1999. Copyright 1999 Wiley-Liss, Inc.