The impact of head orientation with respect to B0: An unexplored source of variance in diffusion MRI

Abstract

Recently observed anisotropy of compartmental white matter T2-values as a function of tissue orientation w.r.t. B0 in combination with echo-time-dependence of diffusion MRI signals suggest that similar tissue-orientational effects could be expected in standard diffusion tensor measures. In this work we show the change of up to 20-30% in diffusion tensor measures as a function of fibre orientation w.r.t. B0 from in vivo experiments and support these observations by simplified two-compartment white matter signal simulations.