title: Design of multishell sampling schemes with uniform coverage in diffusion MRI.
abstract: OBJECTIVE
  In diffusion MRI, a technique known as diffusion spectrum imaging reconstructs the propagator with a discrete Fourier transform, from a Cartesian sampling of the diffusion signal. Alternatively, it is possible to directly reconstruct the orientation distribution function in q-ball imaging, providing so-called high angular resolution diffusion imaging. In between these two techniques, acquisitions on several spheres in q-space offer an interesting trade-off between the angular resolution and the radial information gathered in diffusion MRI. A careful design is central in the success of multishell acquisition and reconstruction techniques.
  
  
  METHODS
  The design of acquisition in multishell is still an open and active field of research, however. In this work, we provide a general method to design multishell acquisition with uniform angular coverage. This method is based on a generalization of electrostatic repulsion to multishell.
  
  
  RESULTS
  We evaluate the impact of our method using simulations, on the angular resolution in one and two bundles of fiber configurations. Compared to more commonly used radial sampling, we show that our method improves the angular resolution, as well as fiber crossing discrimination.
  
  
  CONCLUSIONS
  We propose a novel method to design sampling schemes with optimal angular coverage and show the positive impact on angular resolution in diffusion MRI.
authors.affiliation: Athena Project-Team, Inria Sophia Antipolis-Méditerranée, Sophia Antipolis, France. caruyer@gmail.com
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Caruyer
authors.forename: Christophe
authors.initials: C
authors.lastname: Lenglet
authors.forename: Guillermo
authors.initials: G
authors.lastname: Sapiro
authors.forename: Rachid
authors.initials: R
authors.lastname: Deriche
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D003627:Data Interpretation, Statistical; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D015233:Models, Statistical; D015203:Reproducibility of Results; D018401:Sample Size; D012680:Sensitivity and Specificity