Reconstruction and frequency mapping with phase-cycled bSSFP

Introduction. Balanced steady-state free precession (bSSFP) imaging is a fast acquisition technique giving high signal with very short repetition times. However, its steady-state is very sensitive to off-resonances (and therefore B0 inhomogeneity), leading to nonuniform intensity and signal voids across the image. Adding a linear increase in the phase to the RF pulses moves the signal voids to different values of off-resonance, therefore the acquisition of multiple images with different phase cycling schemes, and their subsequent combination (by means of maximum intensity projection [1], sum of squares [2], etc.) is an effective way to reduce the impact of these artifacts. In this abstract, we propose the non-linear pixelwise fit of the different phase cycles to the Freeman-Hill formula [3] that describes the bSSFP signal, in order to obtain the corrected signal amplitude together with a B0 map.