Figure 2. Phase dispersion induced by non-rigid body motion.
During a bipolar gradient, the phase of a spin within a voxel is shifted by motion according to [Eq 4]. If the voxel does not move as a rigid body, spins in different locations within the voxel will experience different phase shifts, leading to phase dispersion. Magnitude attenuation from this mechanism will occur in addition to that from diffusion. The Beta*LogNormal distribution models attenuation from bulk motion and attenuation from diffusion separately.