title: Dixon water-fat separation in PROPELLER MRI acquired with two interleaved echoes.
abstract: OBJECTIVE
  To propose a novel combination of robust Dixon fat suppression and motion insensitive PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) MRI.
  
  
  METHODS
  Two different echoes were acquired interleaved in each shot enabling water-fat separation on individual blades. Fat, which was blurred in standard PROPELLER because the water-fat shift (WFS) rotated with the blades, was shifted back in each blade. Additionally, field maps obtained from the water-fat separation were used to unwarp off-resonance-induced shifts in each blade. PROPELLER was then applied to the water, corrected fat, or recombined water-fat blades. This approach was compared quantitatively in volunteers with regard to motion estimation and signal-to-noise ratio (SNR) to a standard PROPELLER acquisition with minimal WFS and fat suppression.
  
  
  RESULTS
  Shifting the fat back in each blade reduced errors in the translation correction. SNR in the proposed Dixon PROPELLER was 21% higher compared with standard PROPELLER with identical scan time. High image quality was achieved even when the volunteers were moving during data acquisition. Furthermore, sharp water-fat borders and image details were seen in areas where standard PROPELLER suffered from blurring when acquired with a low readout bandwidth.
  
  
  CONCLUSIONS
  The proposed method enables motion-insensitive PROPELLER MRI with robust fat suppression and reduced blurring. Additionally, fat images are available if desired.
authors.affiliation: Neuroimaging Research, Barrow Neurological Institute, Phoenix, Arizona, USA.|Philips Healthcare, Cleveland, Ohio, USA.|Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Schär
authors.affiliation: Philips Research, Hamburg, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Eggers
authors.affiliation: Neuroimaging Research, Barrow Neurological Institute, Phoenix, Arizona, USA.
authors.forename: Nicholas R
authors.initials: NR
authors.lastname: Zwart
authors.affiliation: Neuroimaging Research, Barrow Neurological Institute, Phoenix, Arizona, USA.
authors.forename: Yuchou
authors.initials: Y
authors.lastname: Chang
authors.affiliation: Philips Healthcare, Bangalore, Karnataka, India.
authors.forename: Akshay
authors.initials: A
authors.lastname: Bakhru
authors.affiliation: Neuroimaging Research, Barrow Neurological Institute, Phoenix, Arizona, USA.
authors.forename: James G
authors.initials: JG
authors.lastname: Pipe
mesh_terms: D000273:Adipose Tissue; D000328:Adult; D001834:Body Water; D001921:Brain / Q000033:anatomy & histology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008099:Liver / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009038:Motion; D059629:Signal-To-Noise Ratio
keywords: Dixon; PROPELLER; fat suppression; motion correction; off-resonance correction; water-fat separation