A Simple and Analytical Way to Correct for δB0 Inhomogeneity in the Evaluation of B1 Maps Relying on Flip Angle Measurements and Non-Selective Square Pulses

Nicolas Boulant¹, Martijn Cloos¹, Alexis Amadon¹

Efficient mitigation of the radiofrequency inhomogeneity at high field using coil arrays relies on the accurate knowledge of the individual B1 maps. To date, no simple recipe has been formulated to correct for B0 inhomogeneity in the evaluation of the B1 maps themselves. Here we derive a simple analytical approximation to increase the accuracy of the B1 mapping techniques which rely on the measurement of the flip angle using non-selective square pulses, in the presence of B0 variations. In some possibly encountered cases, applying the correction reduces the error of the estimated B1 amplitude from 13 % to 0.2 %.