Abstract #4628

Spin Lock Adiabatic Correction (SLAC) of BIR4 pulses for increased B1-insensitivity at 7T

Edward M Green^1,2, Yasmin Blunck^1,2, James C Korte³, Bahman Tahayori^4,5, Peter M Farrell⁶, and Leigh A Johnston^1,2

¹Dept. of Biomedical Engineering, University of Melbourne, Melbourne, Australia, ²Melbourne Brain Centre Imaging Unit, University of Melbourne, Melbourne, Australia, ³Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Australia, ⁴Department of Medical Physics and Biomedical Engineering, Shiraz University of Medical Sciences, Shiraz, Iran (Islamic Republic of), ⁵Dept. of Medical Physics and Biomedical Engineering, Shiraz University of Medical Sciences, Shiraz, Iran (Islamic Republic of), ⁶Dept. of Electrical and Electronic Engineering, University of Melbourne, Melbourne, Australia

Inhomogeneous B1 excitation impedes image quality, particularly at high field. Adiabatic pulse modulation ameliorates this effect, however super-adiabatic properties can be exploited to further improve performance. Spin Lock Adiabatic Correction (SLAC) pulses can be applied to any adiabatic pulse shape, through reduction of flip angle inaccuracies induced by B1 variability. In this work, SLAC is derived for BIR4 pulse shapes, and the superior performance of SLAC-BIR4 is demonstrated in both simulation and phantom experiments at 7T. The SLAC procedure is an attractive analytical alternative to numerical optimisation of adiabatic pulses.

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