At least two chemical species are imaged using magnetic resonance imaging with signal separation for two chemical species resulting in separate signal datasets for these two chemical species. First and second echo data are acquired at different echo times resulting in a first and second acquired complex dataset. The first and second acquired datasets are modelled by employing a spectral signal model of at least one of the chemical species. The modelling results in a first and second modelled complex dataset. The first and second modelled datasets include a first and second phase error and the separate signal datasets for the two chemical species. From the first and second acquired dataset and the first and second modelled dataset the separate signal datasets for the two chemical species are determined.