Franciszek
Hennel1, Sascha Khler1
1Bruker BioSpin MRI, Ettlingen, Germany
A
method for the mapping of the radio-frequency transmission field is proposed
that derives B1 values from the phase of the signal. The sequence consists of
a block pulse to produce a B1-dependent nutation, followed by an inverse
adiabatic half passage (IAFP) that converts the nutation phase to signal
phase. Two ways to compensate the undesired dephasing caused by the IAFP are
proposed: a rewinder RF pulse, or a matched adiabatic echo. The method
provides an increased dynamic range compared to known phase-based B1-mapping
sequences.