In a method and magnetic resonance tomography apparatus for spatially resolved
measurement of the magnetic high frequency field distribution in the apparatus,
a double echo high frequency pulse sequence with a first excitation pulse following
by at least two refocusing pulses are emitted for generation of a first echo and
a following second echo. At least the excitation pulse is slice selective. In an
excitation layer defined by the slice selective excitation pulse a first echo image
and second echo image are spatially resolved by using suitable gradient pulses
for phase or frequency encoding Using the relationships of the amplitudes of the
first and second echo image in the various locations the flip angles representing
the field strength at the relevant locations in the relevant slice are determined.