Determination of a magnetic resonance - sequence with concentric, circular transmit trajectories

摘要

It is a method for determination of a magnetic resonance - sequence (as) is described, with a pulse arrangement (pa, pa ‘, pa ‘ ‘), which, in at least two spatial directions (x, y) acts selectively a rotationally symmetrical excitation profile (ep) within an object to be examined (o), in order to excite. In this case comprises a hf - excitation pulse (sharpness, ‘ sharpness, ‘ sharpness ‘) of the pulse arrangement (pa, pa ‘, pa ‘ ‘) a sequence of a plurality of hf - component pulses (rf₁, Rf₂, Rf₃, .., Rf_n, .., Rf₈) and parallel to the sequence of hf - component pulses (rf₁, Rf₂, Rf₃, .., Rf_n, .., Rf₈) are so coordinated gradient pulses (gp_x, Gp_y, Gp_x‘, Gp_y‘, Gp_x‘‘, Gp_y‘‘) in the two spatial directions (x, y) that the hf - energy introduction of different hf - partial pulses (rf₁, Rf₂, Rf₃, .., Rf_n, .., Rf₈) in the transmitter - k - space (s_k) in each case on mutually concentric, circular k - space - transmit trajectories (tr₁, Tr₂, Tr₃, .., Tr₈) takes place. In this case, the amplitude (b₁) the envelope of the hf - partial pulses (rf₁, Rf₂, Rf₃, .., Rf_n, .., Rf₈) in each case during the duration (t, t₁, T₂, T₃, .., T_n, .., T₈) a passage of a circular k - space - trajectory (tr₁, Tr₂, Tr₃, .., Tr₈) constant. In addition, a method for operating and a method for calibrating a magnet resonance system (1), a control sequence determination of a direction (22) for determining a magnetic resonance - sequence (as) as well as a magnet resonance system (1) with such a control sequence determination of a direction (22) is described.