title: Desynchronization of Cartesian k-space sampling and periodic motion for improved retrospectively self-gated 3D lung MRI using quasi-random numbers.
abstract: To demonstrate that desynchronization between Cartesian k-space sampling and periodic motion in free-breathing lung MRI improves the robustness and efficiency of retrospective respiratory self-gating.
  
  
  
  Desynchronization was accomplished by reordering the phase (ky) and partition (kz) encoding of a three-dimensional FLASH sequence according to two-dimensional, quasi-random (QR) numbers. For retrospective respiratory self-gating, the k-space center signal (DC signal) was acquired separately after each encoded k-space line. QR sampling results in a uniform distribution of k-space lines after gating. Missing lines resulting from the gating process were reconstructed using iterative GRAPPA. Volunteer measurements were performed to compare quasi-random with conventional sampling. Patient measurements were performed to demonstrate the feasibility of QR sampling in a clinical setting.
  
  
  
  The uniformly sampled k-space after retrospective gating allows for a more stable iterative GRAPPA reconstruction and improved ghost artifact reduction compared with conventional sampling. It is shown that this stability can either be used to reduce the total scan time or to reconstruct artifact-free data sets in different respiratory phases, both resulting in an improved efficiency of retrospective respiratory self-gating.
  
  
  
  QR sampling leads to desynchronization between repeated data acquisition and periodic respiratory motion. This results in an improved motion artifact reduction in shorter scan time. Magn Reson Med 77:787-793, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Department of Radiation Oncology, University of Würzburg, Germany.|Department of Experimental Physics 5, University of Würzburg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Weick
authors.affiliation: Department of Experimental Physics 5, University of Würzburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Völker
authors.affiliation: Department of Radiation Oncology, University of Würzburg, Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Hemberger
authors.affiliation: Department of Experimental Physics 5, University of Würzburg, Germany.
authors.forename: Cord
authors.initials: C
authors.lastname: Meyer
authors.affiliation: Max-Planck-Institute for Biological Cybernetics, University of Tübingen, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Ehses
authors.affiliation: Department of Radiation Oncology, University of Würzburg, Germany.
authors.forename: Bülent
authors.initials: B
authors.lastname: Polat
authors.affiliation: Research Center for Magnetic Resonance Bavaria, Würzburg, Germany.
authors.forename: Felix A
authors.initials: FA
authors.lastname: Breuer
authors.affiliation: Research Center for Magnetic Resonance Bavaria, Würzburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Blaimer
authors.affiliation: Department of Radiology, Allgemeines Krankenhaus Celle, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Fink
authors.affiliation: Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Germany.
authors.forename: Lothar R
authors.initials: LR
authors.lastname: Schad
authors.affiliation: Department of Radiation Oncology, University of Würzburg, Germany.
authors.forename: Otto A
authors.initials: OA
authors.lastname: Sauer
authors.affiliation: Department of Radiation Oncology, University of Würzburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Flentje
authors.affiliation: Department of Experimental Physics 5, University of Würzburg, Germany.|Department of Radiology, Allgemeines Krankenhaus Celle, Germany.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Jakob
mesh_terms: D000328:Adult; D000465:Algorithms; D016477:Artifacts; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008168:Lung / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009068:Movement / Q000502:physiology; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods*
keywords: 4D imaging; lung imaging; motion artifact reduction; quasi-random sampling; retrospective self-gating