Open AccessThe importance of k ‐space trajectory on off‐resonance artifact in segmented echo‐planar imaging
Author(s) -
Bender Jacob A.,
Ahmad Rizwan,
Simonetti Orlando P.
Publication year - 2013
Publication title -
concepts in magnetic resonance part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.229
H-Index - 49
eISSN - 1552-5023
pISSN - 1546-6086
DOI - 10.1002/cmr.a.21255
Subject(s) - artifact (error) , trajectory , imaging phantom , planar , echo planar imaging , offset (computer science) , computer science , resonance (particle physics) , physics , computer vision , magnetic resonance imaging , optics , computer graphics (images) , medicine , particle physics , astronomy , radiology , programming language
Segmented interleaved echo planar imaging (EPI) is a highly efficient data acquisition technique; however, EPI is sensitive to artifacts from off‐resonance spins. The choice of k‐space trajectories is important in determining how off‐resonance spins contribute to image artifacts. Top‐down and center‐out trajectories are theoretically analyzed, simulated, implemented, and tested in phantom and volunteer experiments. Theoretical results show off‐resonance artifact manifests as a simple positional shift for the top‐down trajectory, while for the center‐out trajectory off‐resonance artifact manifests as a splitting of the object, which entails both shift and blurring. These results were validated using simulation and phantom scan data where a frequency‐offset was introduced ranging from −300 Hz to +300 Hz. As predicted by the theoretical results, inferior image quality was observed for the center‐out trajectory in a single volunteer. Off‐resonance produces more severe and complex artifacts with the center‐out trajectory than the top‐down trajectory. © 2013 Wiley Periodicals, Inc. Concepts Magn Reson Part 42A: 23–31, 2013.