title: Improved motion correction in PROPELLER by using grouped blades as reference.
abstract: OBJECTIVE
  To develop a robust reference generation method for improving PROPELLER (Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction) reconstruction.
  
  
  METHODS
  A new reference generation method, grouped-blade reference (GBR), is proposed for calculating rotation angle and translation shift in PROPELLER. Instead of using a single-blade reference (SBR) or combined-blade reference (CBR), our method classifies blades by their relative correlations and groups similar blades together as the reference to prevent inconsistent data from interfering the correction process. Numerical simulations and in vivo experiments were used to evaluate the performance of GBR for PROPELLER, which was further compared with SBR and CBR in terms of error level and computation cost.
  
  
  RESULTS
  Both simulation and in vivo experiments demonstrate that GBR-based PROPELLER provides better correction for random motion or bipolar motion comparing with SBR or CBR. It not only produces images with lower error level but also needs less iteration steps to converge.
  
  
  CONCLUSIONS
  A grouped-blade for reference selection was investigated for PROPELLER MRI. It helps to improve the accuracy and robustness of motion correction for various motion patterns.
authors.affiliation: Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University, Beijing, People's Republic of China.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Liu
authors.forename: Zhe
authors.initials: Z
authors.lastname: Zhang
authors.forename: Kui
authors.initials: K
authors.lastname: Ying
authors.forename: Chun
authors.initials: C
authors.lastname: Yuan
authors.forename: Hua
authors.initials: H
authors.lastname: Guo
mesh_terms: D016477:Artifacts; D001931:Brain Mapping / Q000295:instrumentation* / Q000379:methods*; D003198:Computer Simulation; D004867:Equipment Design; D064368:Healthy Volunteers; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D009038:Motion; D010363:Pattern Recognition, Automated; D012680:Sensitivity and Specificity
keywords: MRI; PROPELLER; pattern classification; reference generation; rigid motion correction