ACCURATE ODF RECONSTRUCTION IN Q-BALL IMAGING By

Introduction: Q-ball imaging (Tuch 2004) is a high angular resolution diffusion MR imaging technique proven successful in resolving multiple intravoxel fiber orientations. Standard computations of the orientation distribution function (ODF, the probability of diffusion in a given direction) from q-ball use radial projections and do not consider the solid angle, resulting in distributions different from the true ODFs. Moreover, these distributions are not normalized, and tend to be very smooth. This makes it very difficult to identify maxima, and post-processing (sharpening) is generally required. We derive a new formula for the true ODF, which is dimensionless, normalized, and efficiently computable from q-ball acquisition protocols.