SSFP banding artefact removal in large FOV images at 3T

Introduction Balanced steady state free precession (b-SSFP) sequences with large flip angles (between 40o and 70o) are very attractive for abdominal imaging because they provide high signal, a “T2” like contrast and have short TR’s (<10 ms) which are necessary to produce an entire scan within one breathhold. However, they are limited by banding artefacts which appear as bright and dark stripes in the images, and result from the dependence of the frequency response function (FRF) on the amount of dephasing experienced by the spins during each TR. At 3 T (and higher field strengths) the increased inhomogeneity of B0 enhances banding artefacts and make, until now, b-SSFP sequences practically useless for large field of view (FOV) abdominal images. Shortening the TR is the most straightforward way to minimize banding artefacts but at 3 T this is often problematic at such large flip angles because of specific absorption rate (SAR) constraints. In [1], a method based on combining scans with different phase cycling schemes is proposed to correct for banding artefacts. It is originally applied to images of the brain and spinal cord obtained with a 1 T scanner and its advantage, when considering higher field strengths, is that it does not impose constraints on TR. Here, its ability to obtain artefact free large FOV b-SSFP abdominal images at 3 T is shown.