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Adiabatic inversion pulses for myocardial T1 mapping
Author(s) -
Kellman Peter,
Herzka Daniel A.,
Hansen Michael Schacht
Publication year - 2014
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.24793
Subject(s) - inversion (geology) , tangent , adiabatic process , amplitude , mathematics , mathematical analysis , physics , optics , geometry , geology , quantum mechanics , paleontology , structural basin
Purpose 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. Magn Reson Med 71:1428–1434, 2014. © 2013 Wiley Periodicals, Inc .