title: Fast multistation water/fat imaging at 3T using DREAM-based RF shimming.
abstract: OBJECTIVE
  To show the effect, efficiency, and image quality improvements achievable by Dual Refocusing Echo Acquisition Mode (DREAM)-based B1+ shimming in whole-body magnetic resonance imaging (MRI) at 3T using the example of water/fat imaging.
  
  
  METHODS
  3D multistation, dual-echo mDixon gradient echo imaging was performed in 10 healthy subjects on a clinical 3T dual-transmit MRI system using station-to-station adapted B1+ shimming based on fast DREAM B1+ mapping. Whole-body data were obtained using conventional quadrature excitation and station-by-station adapted DREAM-based B1+ shimmed excitation, along with the corresponding B1+ maps for both excitation modes to assess image quality and radiofrequency (RF) performance.
  
  
  RESULTS
  Station-dependent DREAM-based B1+ shimming showed significantly improved image quality in the stations covering the upper legs, pelvis, and upper body region for all subjects (P < 0.02). This finding is supported by corresponding B1+ maps showing an improved B1+ homogeneity and a more precise flip angle in the DREAM-based B1+ shimmed excitation (P < 0.01). Furthermore, the very short dual-channel DREAM B1+ mapping times of less than 2 seconds facilitate quick B1+ shimming.
  
  
  CONCLUSIONS
  Station-dependent DREAM-based B1+ shimming improved RF performance and image quality and is therefore a promising technique for whole-body multistation imaging applications.
authors.affiliation: Department of Radiology, C.J. Gorter Center for High Field MRI, LUMC, Leiden, the Netherlands.
authors.forename: Melissa T
authors.initials: MT
authors.lastname: Hooijmans
authors.affiliation: Department of Radiology, Division of Image Processing, LUMC, Leiden, the Netherlands.
authors.forename: Oleh
authors.initials: O
authors.lastname: Dzyubachyk
authors.affiliation: Philips Research Laboratories, Hamburg, Germany.
authors.forename: Kay
authors.initials: K
authors.lastname: Nehrke
authors.affiliation: Philips Research Laboratories, Hamburg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Koken
authors.affiliation: Department of Radiology, C.J. Gorter Center for High Field MRI, LUMC, Leiden, the Netherlands.
authors.forename: Maarten J
authors.initials: MJ
authors.lastname: Versluis
authors.affiliation: Department of Radiology, C.J. Gorter Center for High Field MRI, LUMC, Leiden, the Netherlands.
authors.forename: Hermien E
authors.initials: HE
authors.lastname: Kan
authors.affiliation: Department of Radiology, C.J. Gorter Center for High Field MRI, LUMC, Leiden, the Netherlands.|Philips Research Laboratories, Hamburg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Börnert
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology* / Q000378:metabolism*; D000465:Algorithms; D001834:Body Water / Q000378:metabolism*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D011846:Radio Waves; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D051598:Whole Body Imaging / Q000379:methods*
keywords: 3T; DREAM; RF shimming; whole-body imaging