title: The Importance ofk-Space Trajectory on Off-Resonance Artifact in Segmented Echo-Planar Imaging.
abstract: 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.
authors.affiliation: Department of Biomedical Engineering, The Ohio State University, Columbus, OH ; Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH.
authors.forename: Jacob A
authors.initials: JA
authors.lastname: Bender
authors.affiliation: Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH ; Department of Electrical and Computer Engineering, The Ohio State University, Columbus, OH.
authors.forename: Rizwan
authors.initials: R
authors.lastname: Ahmad
authors.affiliation: Department of Biomedical Engineering, The Ohio State University, Columbus, OH ; Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH ; Department of Internal Medicine, Division of Cardiovascular Medicine, The Ohio State University, Columbus, OH ; Department of Radiology, The Ohio State University, Columbus, OH.
authors.forename: Orlando P
authors.initials: OP
authors.lastname: Simonetti
keywords: echo-planar imaging; k-space trajectory; off-resonance