A Modified EPI Sequence for High-Resolution Imaging at Ultra-Short Echo Time

A robust modification of echo-planar imaging dubbed double-shot echo-planar imaging with center-out trajectories and intrinsic navigation (DEPICTING) is proposed, which permits imaging at ultra-short echo time. The k-space data is sampled by two center-out trajectories with a minimal delay achieving a temporal efficiency similar to conventional single-shot echo-planar imaging. Intersegment phase and intensity imperfections are corrected by exploiting the intrinsic navigator information from both central lines, which are subsequently averaged for image reconstruction. Phase errors induced by inhomogeneities of the main magnetic field are corrected in k-space, recovering the superior point-spread function achieved with center-out trajectories. The minimal echo time (< 2 msec) is nearly independent of the acquisition matrix permitting applications, which simultaneously require high spatial and temporal resolution. Examples of demonstrated applications include anatomical imaging, BOLD-based functional brain mapping, and quantitative perfusion imaging. Magn Reson Med 65:165-175, 2011. (c) 2010 Wiley-Liss, Inc.