Karla L. Miller1, Peter Jezzard1, Stephen M. Smith1
1FMRIB Centre, Oxford University, Oxford, Oxon, UK
A new contrast mechanism based on balanced SSFP is presented, which is hypothesized to be sensitive to tissue microstructure. The balanced SSFP profile is theoretically symmetric if only T1, T2 and diffusion effects are considered. However, in the presence of an asymmetric lineshape, the profile can become asymmetric. Strong asymmetries are observed in white matter, and maps of these asymmetries are robust and reproducible across subjects. White matter fibres parallel to B0 have significantly reduced asymmetry, indicating that the largest asymmetries may relate to tract geometry. This novel form of contrast may be a sensitive marker to white matter integrity.