Eddy-current compensated diffusion weighting with a single refocusing RF pulse

Abstract

A modification of the Stejskal-Tanner diffusion-weighting preparation with a single refocusing RF pulse is presented which involves three gradient lobes that can be adjusted to null eddy currents with any given decay rate to reduce geometric distortions in diffusion-weighted echo-planar imaging (EPI). It has a very similar compensation performance as the commonly used double-spin-echo preparation but (i) is less sensitive to flip angle imperfections, e.g. along the slice profile, and B1 inhomogeneities and (ii) can yield shorter echo times for moderate b values, notably for longer echo trains as required for higher spatial resolution. It therefore can provide an increased signal-to-noise ratio as is simulated numerically and demonstrated experimentally in water phantoms and the human brain for standard EPI (2.0 x 2.0 mm2) and high-resolution EPI of inner field-of-views using 2D-selective RF excitations (0.5 x 1.0 mm2). Thus, the presented preparation may help to overcome current limitations of diffusion-weighted EPI, in particular at high static magnetic fields. © 2009 Wiley-Liss, Inc.