Method and magnetic resonance apparatus for generating a parameter map to compensate local inhomogeneities in the basic magnetic field

摘要

In a method and a controller for generating a parameter map for a target volume in an examination object, that represents a field deviation from the resonance frequency of a first spectral component of tissue of object in a magnetic resonance tomography scanner, a spatial region of the object, which includes at least the target volume, is excited. At least three echo signals are formed, wherein a first echo time difference between two the echo signals is chosen such that the phase evolutions of the signals of a second spectral component of the tissue differ, during the first echo time difference, from the first spectral component substantially by 2π, and an echo time of at least a further one of the echo signals is chosen such that it lies between the echo times of the two echo signals having the first echo time difference. Raw data are then acquired from the three echo signals, and the parameter map is then generated therefrom.