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

Stefan Hetzer¹, Toralf Mildner¹, Harald E. Mller¹

An EPI modification which achieves high SNR is proposed. k-space is sampled in two tiles along phase-encoding direction by center-out trajectories with a minimal delay achieving a similar efficiency as single-shot EPI. Inter-segment phase and intensity imperfections can be easily corrected with the information from both central lines, which are subsequently averaged for SNR optimization. Phase errors from field inhomogeneities are corrected in the Fourier domain, recovering the superior point-spread function. The ultra-short echo time (≈2 ms) is nearly independent of the resolution permitting a variety of applications that require high spatial and temporal resolution.