title: Balanced UTE-SSFP for 19F MR imaging of complex spectra.
abstract: OBJECTIVE
  A novel technique for highly sensitive detection of multiresonant fluorine imaging agents was designed and tested with the use of dual-frequency 19F/1H ultrashort echo times (UTE) sampled with a balanced steady-state free precession (SSFP) pulse sequence and three-dimensional (3D) radial readout.
  
  
  METHODS
  Feasibility of 3D radial balanced UTE-SSFP imaging was demonstrated for a phantom comprising liquid perfluorooctyl bromide (PFOB). Sensitivity of the pulse sequence was measured and compared with other sequences imaging the PFOB (CF2 )6 line group including UTE radial gradient-echo (GRE) at α = 30°, as well as Cartesian GRE, balanced SSFP, and fast spin-echo (FSE). The PFOB CF3 peak was also sampled with FSE.
  
  
  RESULTS
  The proposed balanced UTE-SSFP technique exhibited a relative detection sensitivity of 51 μmolPFOB(-1) min(-1/2) (α = 30°), at least twice that of other sequence types with either 3D radial (UTE GRE: 20 μmolPFOB(-1) min(-1/2) ) or Cartesian k-space filling (GRE: 12 μmolPFOB(-1) min(-1/2) ; FSE: 16 μmolPFOB(-1) min(-1/2) ; balanced SSFP: 23 μmolPFOB(-1) min(-1/2) ). In vivo imaging of angiogenesis-targeted PFOB nanoparticles was demonstrated in a rabbit model of cancer on a clinical 3 Tesla scanner.
  
  
  CONCLUSIONS
  A new dual 19F/1H balanced UTE-SSFP sequence manifests high SNR, with detection sensitivity more than two-fold better than traditional techniques, and alleviates imaging problems caused by dephasing in complex spectra.
authors.affiliation: Department of Biomedical Engineering, Washington University in St. Louis, Missouri, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Goette
authors.affiliation: Philips Research Europe, Hamburg, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Keupp
authors.affiliation: Philips Research Europe, Hamburg, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Rahmer
authors.affiliation: Department of Biomedical Engineering, Washington University in St. Louis, Missouri, USA.|Department of Medicine, Washington University in St. Louis, Missouri, USA.
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Lanza
authors.affiliation: Department of Biomedical Engineering, Washington University in St. Louis, Missouri, USA.|Department of Medicine, Washington University in St. Louis, Missouri, USA.
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Wickline
authors.affiliation: Department of Biomedical Engineering, Washington University in St. Louis, Missouri, USA.|Philips Healthcare, Cleveland, Ohio, USA.
authors.forename: Shelton D
authors.initials: SD
authors.lastname: Caruthers
mesh_terms: D000465:Algorithms; D000818:Animals; D005240:Feasibility Studies; D005260:Female; D066235:Fluorine-19 Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D009374:Neoplasms, Experimental / Q000473:pathology*; D019047:Phantoms, Imaging; D011817:Rabbits; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
keywords: 19F MRI; balanced steady state free precession; molecular imaging; ultra short echo time