Rapid Frequency Offset Mapping with the Half Fourier Acquisition Single-Shot Turbo Spin-Echo with the Selective Parity Approach

Frequency Offset (FO) maps are widely used to correct image distortion and signal loss when magnetic resonance imagine sequences, which are sensitive to field inhomogeneities, are used. The state-of-the-art requires several image acquisitions at different echo times to map the off-resonance frequencies generated by the magnetic field inhomogeneities. This work compares the state-of-the-art method using a modified Half Fourier Acquisition Single-Shot Turbo Spin-Echo (HASTE) sequence with a new proposed method using a Selective Parity (SP) HASTE approach to create FO maps. The SP-HASTE approach needs one single image acquisition followed by image processing to create a frequency offset map. In the experiment different echo times acquisitions were performed to compare the resulting frequency offset maps. Statistical comparison of the results of the SP-HASTE approach and the HASTE were done revealing a comparable agreement between the two methods. They showed a large correlation with values of 1+/-0.05 in the linear regression and not significant frequency differences. The SP-HASTE approach showed a significant reduction in the necessary time to achieve a frequency offset map using one single image acquisition.