In a method to operate a magnetic resonance (MR) system to acquire MR data, an RF excitation pulse is radiated followed by repeated, chronologically sequential implementation of the following steps in order to respectively acquire the MR data of an echo train. A refocusing pulse is radiated, a phase coding gradient is activated, and an additional magnetic field gradient for spatial coding is activated in a direction that is orthogonal to the direction of the phase coding gradient in order to read out the MR data of a k-space line. A k-space line in the k-space center is acquired at a predetermined echo time. A first half of k-space is acquired by entering data into k-space lines of the respective echo train, the data being acquired before the echo time. A second half of k-space is acquired by entering data into k-space lines of the respective echo train, this data having been acquired after the echo time. The k-space lines in the first half of k-space have a first density while the k-space lines in the second half of k-space have a second density that differs from the first density.