The invention relates to a method of MR imaging, wherein a portion of a body placed in the examination volume of a MR device is subjected to an imaging sequence of RF pulses and switched magnetic field gradients. The imaging sequence is a stimulated echo sequence including i) two preparation RF pulses (±) radiated toward the portion of the body during a preparation period (21), and ii) reading RF pulses (²) radiated toward the portion of the body during an acquisition period (22) temporally subsequent to the preparation period (21). FID signals (I 1 ) and stimulated echo signals (I 2 ) are acquired during the acquisition period (22). A B 1 map indicating the spatial distribution of the RF field of the RF pulses within the portion of the body is derived from the acquired FID (I 1 ) and stimulated echo (I 2 ) signals.
