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Parallel Transmit Pulse Design

One of the current fields of research in MRI concerns the design of spatially selective radio frequency pulses for parallel transmission. Multiple motivations drive the need for better understanding and advancing the methodology. They fall in the three categories of enhancing the precision of imaging results, acceleration of data acquisition and, mitigation of radio frequency field distortions at high and ultra high frequencies.

   Sample 3D excitationThis small tip angle excitation of a cube within a spherical NiSO4 solution was achieved with 8 individual RF channels along a 3D spiral trajectory lasting 5.12 ms. The pulses for this excitaton where computed with the conventional method used in B1DER [Ref 1].

Sample 2D excitation The pulses for this 8 channel excitation simulation were computed with the aformentioned new approach within few seconds on a modern workstation to excite the logo of the research centre. The pattern was excited covering a radial field of excitation of 192 diameter within 5ms along a 6-fold undersampled spiral trajectory.