Isotropic Steady State Diffusion Weighted Imaging

Introduction Steady-state diffusion-weighted imaging enables high-SNR, high-resolution diffusion images of brain and is potentially effective in the diagnosis of stroke location [1]. However, white matter anisotropic tissue contrast can mask out a real stroke location. In order to get rid of the anisotropic effect of diffusion, the whole diffusion tensor is acquired and its trace is derived. Alternately, in standard diffusion sequences such as diffusion weighted single shot EPI or diffusion weighted IEPI, isotropic diffusion weighting can be applied to acquire isotropic diffusion weighted images [2, 3]. Unlike the standard diffusion sequences, which use a bipolar gradient per TR, SS-DWI uses a single unbalanced diffusion gradient. Therefore, isotropic diffusion weighting cannot be created in a conventional way. In this work, we introduce a new method for creating isotropic diffusion weighting in steady-state free precession imaging.