title: Phase labeling using sensitivity encoding (PLUS): data acquisition and image reconstruction for geometric distortion correction in EPI.
abstract: Geometric distortion caused by magnetic field inhomogeneity is generally an inevitable tradeoff for fast MRI acquisitions using echo-planar imaging. Most of the existing distortion-correction techniques require separate scans for field maps in order to correct the distortion contained in a measurement. A drawback of these current techniques is that the field map scans and the measurement can capture different patient positions, which invalidates the stationary condition. A new method was developed in this work to correct geometric distortion by using local phase shifts derived directly from the measurement itself, without the need of extra field map scans. This self-sufficient method takes advantage of parallel imaging and k-space trajectory modification to produce multiple images from a single acquisition. The measurement is also used to derive sensitivity maps for parallel imaging reconstruction. The derived phase shifts are retrospectively applied to the measurement for correction of geometric distortion in the measurement itself. The proposed method was successfully demonstrated using experimental data from a phantom and a human brain.
authors.affiliation: Department of Radiology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
authors.forename: Udomchai
authors.initials: U
authors.lastname: Techavipoo
authors.forename: John
authors.initials: J
authors.lastname: Lackey
authors.forename: Jianrong
authors.initials: J
authors.lastname: Shi
authors.forename: Thomas
authors.initials: T
authors.lastname: Leist
authors.forename: Song
authors.initials: S
authors.lastname: Lai
mesh_terms: D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology*; D004578:Electron Spin Resonance Spectroscopy / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity