title: De-aliasing for signal restoration in Propeller MR imaging.
abstract: Objects falling outside of the true elliptical field-of-view (FOV) in Propeller imaging show unique aliasing artifacts. This study proposes a de-aliasing approach to restore the signal intensities in Propeller images without extra data acquisition.
  
  
  
  Computer simulation was performed on the Shepp-Logan head phantom deliberately placed obliquely to examine the signal aliasing. In addition, phantom and human imaging experiments were performed using Propeller imaging with various readouts on a 3.0 Tesla MR scanner. De-aliasing using the proposed method was then performed, with the first low-resolution single-blade image used to find out the aliasing patterns in all the single-blade images, followed by standard Propeller reconstruction. The Propeller images without and with de-aliasing were compared.
  
  
  
  Computer simulations showed signal loss at the image corners along with aliasing artifacts distributed along directions corresponding to the rotational blades, consistent with clinical observations. The proposed de-aliasing operation successfully restored the correct images in both phantom and human experiments.
  
  
  
  The de-aliasing operation is an effective adjunct to Propeller MR image reconstruction for retrospective restoration of aliased signals.
authors.affiliation: Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan.
authors.forename: Su-Chin
authors.initials: SC
authors.lastname: Chiu
authors.affiliation: Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong; Brain Imaging and Analysis Center, Duke University Medical Center, Durham, North Carolina, USA.
authors.forename: Hing-Chiu
authors.initials: HC
authors.lastname: Chang
authors.affiliation: Brain Imaging and Analysis Center, Duke University Medical Center, Durham, North Carolina, USA.
authors.forename: Mei-Lan
authors.initials: ML
authors.lastname: Chu
authors.affiliation: Graduate Institute of Medical Informatics, National Cheng-Kung University, Tainan, Taiwan.
authors.forename: Ming-Long
authors.initials: ML
authors.lastname: Wu
authors.affiliation: Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan.
authors.forename: Hsiao-Wen
authors.initials: HW
authors.lastname: Chung
authors.affiliation: Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan. Electronic address: yrlin@mail.ntust.edu.tw.
authors.forename: Yi-Ru
authors.initials: YR
authors.lastname: Lin
mesh_terms: D016477:Artifacts; D003198:Computer Simulation; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D012189:Retrospective Studies
keywords: Aliasing artifacts; Propeller MR imaging; Signal re-distribution; Signal restoration