string: Although these twomethods described above were originally proposed for single-shell data, they can be generalized for multi-shell data using two different approaches:
   ‚Ä¢ First fit diffusion models, such as DTI (Basser et al., 1994) or Spherical Polar Fourier Imaging (Assemlal et al., 2009; Cheng et al., 2010b), to high-anisotropy diffusion signal E(q) in R3.