Conference Proceedings

B1 Insensitive Genetically Altered Refocusing Pulses for Ultrahigh Field Spin Echo Imaging

Aaron Christopher Hurley, Andrew Peters, Uwe Aickelin, Bai Li, Penny Gowland

ISMRM Stockholm, Sweden, May, 2010 | ISMRM | Published : 2010

Abstract

B1 inhomogeneity at ultrahigh field limits the use of spin echo pulses. In the past adiabatic refocusing pulses have been proposed to provide B1 insensitivity but are generally rather long for imaging applications. Urgurbil et al. [1] proposed the use of a Numerically Optimised Modulation (NOM) scheme to improve the adiabaticity over the whole length of a BIR4 pulse and this method provides better performance for shorter pulses. NOM resamples the AM and FM functions with reference to the adiabatic condition and is restricted to looking at on-resonance effects. Following from this work, we attempted to optimize the resampling function via a Genetic Algorithm. The evaluation function considers..

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University of Melbourne Researchers