title: Adiabatic inversion pulses for myocardial T1 mapping.
abstract: OBJECTIVE
  To evaluate the error in T1 estimates using inversion-recovery-based T1 mapping due to imperfect inversion and to perform a systematic study of adiabatic inversion pulse designs in order to maximize inversion efficiency for values of transverse relaxation (T2) in the myocardium subject to a peak power constraint.
  
  
  METHODS
  The inversion factor for hyperbolic secant and tangent/hyperbolic tangent adiabatic full passage waveforms was calculated using Bloch equations. A brute-force search was conducted for design parameters: pulse duration, frequency range, shape parameters, and peak amplitude. A design was selected that maximized the inversion factor over a specified range of amplitude and off-resonance and validated using phantom measurements. Empirical correction for imperfect inversion was performed.
  
  
  RESULTS
  The tangent/hyperbolic tangent adiabatic pulse was found to outperform hyperbolic secant designs and achieve an inversion factor of 0.96 within ±150 Hz over 25% amplitude range with 14.7 µT peak amplitude. T1 mapping errors of the selected design due to imperfect inversion was ∼4% and could be corrected to <1%.
  
  
  CONCLUSIONS
  Nonideal inversion leads to significant errors in inversion-recovery-based T1 mapping. The inversion efficiency of adiabatic pulses is sensitive to transverse relaxation. The tangent/hyperbolic tangent design achieved the best performance subject to the peak amplitude constraint.
authors.affiliation: National Institutes of Health, Department of Health and Human Services, National Heart, Lung and Blood Institute, Bethesda, Maryland, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Kellman
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Herzka
authors.forename: Michael Schacht
authors.initials: MS
authors.lastname: Hansen
mesh_terms: D000465:Algorithms; D006321:Heart / Q000033:anatomy & histology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: MOLLI; MRI; T1 mapping; adiabatic inversion