title: Improved slice-selective adiabatic excitation.
abstract: OBJECTIVE
  The purpose of this work is to design an improved Slice-selective Tunable-flip AdiaBatic Low peak-power Excitation (STABLE) pulse with shorter duration and increased off-resonance immunity to make it suitable for use in a greater range of applications and at higher field strengths. An additional aim is to design a variant of this pulse to achieve B1 -insensitive, fat-suppressed excitation.
  
  
  METHODS
  The adiabatic SLR algorithm was used to generate a more uniform spectral pulse envelope for this improved radiofrequency pulse for adiabatic slice-selective excitation, called STABLE-2. Pulse parameters were adjusted to design a version of STABLE-2 with a spectral null centered on lipids.
  
  
  RESULTS
  In vivo images obtained of the human brain at 3 and 7 T demonstrate that STABLE-2 provides robust, uniform, slice-selective excitation over a range of B1 values. Phantom and in vivo knee images obtained at 3 T demonstrate the effectiveness of STABLE-2 for fat suppression.
  
  
  CONCLUSIONS
  STABLE-2 achieves B1 -insensitive slice-selective excitation while providing greater off-resonance immunity and a shorter pulse duration, when compared to the original STABLE pulse. In particular, the 9.8-ms STABLE-2 pulse provides slice selectivity over 120 Hz whereas the 21-ms STABLE pulse is limited to 80 Hz off-resonance. B1 -Insensitive fat-suppressed excitation may also be achieved by using a variant of this pulse.
authors: Department of Radiology, Stanford University, Stanford, California, USA.
authors: Priti
authors: P
authors: Balchandani
authors: Gary
authors: G
authors: Glover
authors: John
authors: J
authors: Pauly
authors: Daniel
authors: D
authors: Spielman
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology*; D000465:Algorithms; D001921:Brain / Q000033:anatomy & histology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007719:Knee Joint / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique
keywords: B1-insensitive; RF excitation; STABLE; Shinnar Le-Roux; adiabatic; fat suppression; off-resonance; slice-selective
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