title: Optimized spectrally selective steady-state free precession sequences for cartilage imaging at ultra-high fields.
abstract: OBJECTIVE
  Fat suppressed 3D steady-state free precession (SSFP) sequences are of special interest in cartilage imaging due to their short repetition time in combination with high signal-to-noise ratio. At low-to-high fields (1.5-3.0 T), spectral spatial (spsp) radio frequency (RF) pulses perform superiorly over conventional saturation of the fat signal (FATSAT pulses). However, ultra-high fields (7.0 T and more) may offer alternative fat suppression techniques as a result of the increased chemical shift.
  
  
  METHODS
  Application of a single, frequency selective, RF pulse is compared to spsp excitation for water (or fat) selective imaging at 7.0 T.
  
  
  RESULTS
  For SSFP, application of a single frequency selective RF pulse for selective water or fat excitation performs beneficially over the commonly applied spsp RF pulses. In addition to the overall improved fat suppression, the application of single RF pulses leads to decreased power depositions, still representing one of the major restrictions in the design and application of many pulse sequences at ultra-high fields.
  
  
  CONCLUSIONS
  The ease of applicability and implementation of single frequency selective RF pulses at ultra-high-fields might be of great benefit for a vast number of applications where fat suppression is desirable or fat-water separation is needed for quantification purposes.
authors.affiliation: MR Physics, Department of Medical Radiology, University of Basel, Petersgraben 4, 4031 Basel, Switzerland. oliver.bieri@unibas.ch
authors.forename: O
authors.initials: O
authors.lastname: Bieri
authors.forename: T C
authors.initials: TC
authors.lastname: Mamisch
authors.forename: S
authors.initials: S
authors.lastname: Trattnig
authors.forename: O
authors.initials: O
authors.lastname: Kraff
authors.forename: M E
authors.initials: ME
authors.lastname: Ladd
authors.forename: K
authors.initials: K
authors.lastname: Scheffler
mesh_terms: D000465:Algorithms; D002138:Calibration; D002356:Cartilage / Q000473:pathology*; D002358:Cartilage, Articular / Q000473:pathology; D003952:Diagnostic Imaging / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D010329:Patella / Q000473:pathology; D019047:Phantoms, Imaging; D011846:Radio Waves; D015203:Reproducibility of Results; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water